But holding cars to the same mechanical rigors as airplanes would make them neigh unaffordable for most That's why most states have an emissions test (to addre

But holding cars to the same mechanical rigors as airplanes would make them neigh unaffordable for most That's why most states have an emissions test (to address the negative externality that individual drivers don't feel a cost to emit pollutants, but society does pay that cost) and a safety test. Most states do not have a general mechanical test. (The definition of what part of 'mechanical' is also 'safety' is not a bright line, so if you're arguing the safety tests sometimes go too far, maybe that's right -- we could ask an actuary who has the data I suppose.)