Well, I think the better looting in perception is a good spot for it. Because without better perception, typically harder to recognize or find things. And usually better perception would in turn make aiming and all for ranged weapons better. So, to me, it feels looting best fits under perception since there isn't some perks outside of the attributes. Bartering under int makes sense though, better negotiation usually goes with a better mind or intelligence.
Though for vehicles, I would find it cool if you got one after some super long quest that requires going to a t5 or t6 POI in the process. That way it's not simple and cars are rare to find working now as is, but someone without int can get one.
So short of them making a "blank" attribute to put random perks under, people will need things across the board. And I don't think they'll do that and all perks will be under an attribute.
I do think there may be some perks that could change attributes, like "The Huntsman" being under fortitude doesn't make much sense to me. Since it's for getting more resources from animals, I would find that being under Perception or Agility due to needing to be able to be quiet to hunt and typically ranged weapons. It almost feels like then I'm having to take an attribute that doesn't seem to match with what I want to do. But I know it's a game, not realism, but since there seems to be some realism mixed in, that's a simple one that doesn't break game play.
--update--
If anything, I'll probably go through and make it go under Perception myself. I'll just mod things as I see fit, add some perks as I want, maybe a few other things. The perks actually interest me a lot and the possibility that it brings.