Per [1], a typical Portland public bus causes about 730 times more road wear than a full size pickup truck (which is about the worst case for road wear from a personal vehicle). How many buses have more than 700 people riding in them?
(I am of course ignoring the scaling for fuel, maintenance, pollution, and traffic costs of personal vehicles; but my point is that most people severely underestimate just how awful the economic case for an underused full size bus is. Now, minibuses and microbuses are a different story; but US public transit systems don't use them.)
You can fit 40-50 people in your car?