I think it is a terrible idea and I will write some reasons why :
1. Traders can't be destructible, because zombies will attack them thanks to their AI programming. It will be frustrating if a trader just dies because a screamer spawned somewhere near them, right?
It could be frustrating if a trader dies, sure. But it would be a temporary frustration, akin to when you don't reach the trader before they close, or when you can't get enough money to buy that one item before they restock. The trader can respawn the next day, creating the illusion that another truck drove in overnight. And, the easier way to implement these food truck-style traders would be to not have a walking talking human at all, but to just spawn the truck and interact with that. In that case, while the truck is technically destructible, zombies have no reason to attack vehicles. So you'd worry about the trader truck being destroyed by zombies about as much as you worry about your 4x4 being destroyed by zombies, which is to say hardly at all.
2. Do you know S.T.A.L.K.E.R.? Sidrovicz sits in his bunker. Docs have bunkers, too. The rest sit in faction bases. It would be really hard to create "protection" against zombies using NPCs. Traders in 7DTD work like in S.T.A.L.K.E.R. or an MMO, and it's totally logical. They have a place to keep stuff, a field where they grow food, etc. Just add a few guard NPCs (I made a topic about how I see this).
So this is logical, that they sit in a safe place and just send their men to get stuff and sell to others. It's stupid that zombies can destroy stone, bricks etc.... Zombies destroying everything is less immersive but it's a logical mechanic. Trader's bases are immersive but not a logical mechanic.... Zombies should only destroy windows, doors, meshes, and everything that normal people can destroy with their bare hands and time. But then players will just making stone or bricks everywhere, "exploiting" the system.
Tracks are an even stupider idea. Of course cars like in "Dawn of the Dead" make sense... for a while. They just wanted to get into ships. In the near term, they have a lot of fuel, right? But in the long term, it is just stupid, as in the Resident Evil films. Trucks burn a lot of fuel, and they can be easily stopped by wrecks, land mines, zombies, or bandits. So fuel will run out really soon, or something will stop them. So "stationary" bases are more logical. Just put guards on the walls and near the gate. So yeah teleportation is stupid and can be made better, like with a guard shooting at you when you attack a base, or they start shouting to go away at night and if you don't do this, they will start shooting.
I'm doing my best to understand you. I don't see how the whole 'logically zombies shouldn't destroy hard materials' argument is relevant here. Traders in trucks is a way to do traders that accepts the logic used in the rest of the game: that zombies can destroy anything that's not bedrock. I don't accept that traders need to be protected. The loose end you have to tie up if they're not protected, is what to do if they're destroyed. And traders that respawn somewhere else on a road the next day addresses that problem.
You argue that roaming the apocalypse in a truck is less logical than a sedentary lifestyle with a base and a farm etc. I'd say that's highly subjective. There are whole cultures of nomadic/itinerant peoples active today, including some that make their living through trade, and such groups have survived stretching back into pre-history. I see no reason to think it wouldn't work as a strategy in this post-apocalyptic world. What's one of the easiest ways to avoid all but one type of zombie in 7DtD? Get on a vehicle and drive away. Is fuel a problem? Sure, but does it stop you from using vehicles? No. You scavenge gas from gas stations and fuel barrels, you mine a little oil shale and throw it in a chemistry station you find... it's a challenge but you deal with it. The trader can do the same.
Besides which, this is all theoretical lore stuff. You don't have to see the trader dealing with the problems of acquiring fuel and avoiding obstacles on the highway. You can use your imagination for how he or she deals with those problems on their way to parking and setting up shop in the morning. But you
do have to see the artificial protection the trader gets in the current implementation. You have to hear the zombies banging on the walls, making the 'no damage' sound, constantly reminding you that these traders only survive because they get to break the rules of the game. You can suspend disbelief a lot better when the trader deals with their existential threats 'off screen'.
3. If you want to make them respawn sometimes on the map it can... crash a server with collisions. XD Yep, bugs. Respawning on brick? Crash. In water? Crash. On grass? Crash. So you have two options. 1) The trader truck is something like a truck or bike. This is a good idea, because it will not spawn in something (in 75% cases) but what if you respawn it in air? Well it can fall on something, the physics gets crazy and booom! Crash. 2) It respawns like in Terraria, a "meteor" or "corruption". That will be safer, but it will be programming hell.
4. Okay. You manage to figure out how to make them without blowing up your PC? Cool. Now will be the problem with "where". It will be stupid if they respawn on the edge of a bridge or minefield, right? Or in cities, too, because there are zombies everywhere so the truck goes boom. Desert? Vultures = boom. Wasteland? Dogs = boom.
Okay, I have a plan on how to do all this, which is easier to talk about now that this screenshot of A20 RWG is public.
Note how, unlike in past versions of the game, the cars, street lights, crosswalk etc. are 'aware' of the street: they're positioned and rotated correctly relative to the street. The ability to do that is very powerful, and it means you can effectively put a prefab on the road itself instead of on a lot adjacent to the road.
So what you do is, you make a tiny trader prefab. Really, the only essential part is the panel truck, but you can add a barracks chair under a little awning, with a cooler... let the world builder have fun with it. As part of the random world generation, you put lots of these prefabs all over the roads: say, one every 100 blocks. And then the trick is, when the game begins, these prefabs aren't active. They're just invisible, with no collision, like a quest start node.
When it's time for a trader to 'drive in', the game picks one of these precomputed nodes to 'spawn' the prefab. It's like resetting a POI for a quest: all the blocks in the small prefab override whatever blocks were already there. It doesn't pick a node that's been disturbed, so it doesn't delete your base in the middle of the road or whatever weird thing is in the way there. And this works, because it has lots and lots of nodes to choose from. It'd be practically impossible to screw up every node in the world, and if you do, fine, no trader for you.
So it's all block replacement, like resetting a POI for a quest. No collisions, no spawning in air, no landmines going off, no falling, no crazy physics. And zombies attacking the truck? That's not a thing. Zombies won't target a vehicle in the road. They never have. I don't know where you got that idea. And even if they did, it would be simple to make them not do that. So the trader can spawn in any biome. Heck, maybe a trader in the wasteland offers better stuff due to the heightened risk of meeting them out there. Location, location, location.
5. Okay. You manage to make the "rules" where they can respawn. Cool, but it can break quests. Like - you are going somewhere 2 km and back. You have to bring a quest item back those 2 km. You are going back, 250 meters left and... poof! The trader despawns. Now you go 4 km to the snow biome, hoping this time he will not despawn again and something won't kill you to make the quest a failure.
This probably has the biggest gameplay significance among the points I've seen raised. There would be two ways to lose a trader: they pack up for the night and leave, or their truck is destroyed. Packing up and leaving would be most like what we have now. We're used to the trader closing shop and being inaccessible at night, with a warning shortly before they do. It'd be the same with a traveling trader.
If the trader is destroyed - which wouldn't happen often in practice, outside of PvP - then I'd say any missions with that trader would fail. This seems sensible. You see it in other games, where a mission fails if a character critical to that mission dies. I mean, I have to stress that the zombies don't target vehicles, they target players. And you wouldn't even
need to raise the HP of the panel truck in the game (even though that's a 5 minute change). It already takes quite a beating at 2500 HP. What to do if the truck goes boom is almost more of a technicality, to not leave edge cases unaddressed.
Also, as previously mentioned traders don't have to be the quest givers in the first place. I think they only are because, as the only NPCs, they're the only option. If the game has factions, then maybe all you have to do is turn the quest in to someone, anyone, representing that faction.
