I agree that stepping carelessly on a landmine should probably result in an instant death, but the cheaper landmines might be so poorly put together that they wouldn't actually kill a person so I'll give the developers that.
Though I don't think getting one-shot while looting is necessarily an indication of carelessness. Like Poojam said, players have become increasingly complacent because the sound radii was nerfed so hard. Given that, not many people pay attention to their surroundings anymore. Regardless, I play PUBG so I'm going to compare some simple numbers to that. In PUBG, you can take 2-3 shots even without armor. As you get better and better armor, sometimes you take take 4, 5, or even more shots if the shooter's caliber is low. It gives you enough time to react, get cover, and launch a counter-attack. Maybe you still lose but at least you get a chance to fight back. The only exception is in close-quarters battles where you might be out of luck due to the development speed of the encounter. The maximum punishment for dying in PUBG is just 30 minutes of looting and killing.
The maximum punishment for losing a fight in 7 Days is potentially dozens of hours of work. Literally a 10-20x harsher punishment (if not more), so relatively speaking, I would say at the bare minimum it should take at least as many shots to kill a player in 7 Days as it does in PUBG, if not twice as many. In PUBG a level 3 helmet can take a shot from almost every sniper rifle, and level 3 armor can withstand 3-4 bullets from the strongest assault rifles or a single shotgun slug at point blank range. You should be able to take at least that many shots if you have perfect armor in 7 Days. Basically we need a better balance between the time it takes to ambush someone, for them to react, the fight to take place and the fight to end, and how much you stand to lose by losing the fight. So either you lose less (for example, drop toolbelt but not inventory), or the fights take longer. I prefer a total loss of all items on death, so my vote is to increase the average length of a PvP battle by reducing gun damage significantly.