Really, Bethesda?

Whenever I played Fallout 3 or NV, I always wondered... WHY CAN'T YOU DRIVE A CAR!?! They can't ALL be broken, and the game is filled with roads. I'm just saying, if I were surviving in the wastes, I would ride at least one of the four-fucking-thousand motorcycles or cars that I can only seem to scavenge parts from or blow up.