Those are all private transactions with private business entities, this is not the same as driving on a public road. It's feasible one can buy fuel with no intent to drive (maybe a gas generator in their cabin), get a car repaired (no proof they'll be driving it publicly), or sell you a vehicle (same as mechanic).
Again, what point are you trying to make? Because you're doing a god awful job so far.
EDIT: I suppose I see what you're trying to get at. You're saying that regulation of vehicles isn't comparable to regulation of guns because vehicle are regulated on usage, not on sale, whereas guns are regulated on sale (and to some extent, usage such as hunting, but that isn't necessary right now).
At this point, I'm kind of tired of arguing these points anymore, so I have nothing else to say other than that I stick with my core argument and the idea that traffic laws can't apply to some of you on public roads just makes no god damn sense.