There's a perceptional issue at work. Individual people aren't in control of an airplane. They're stuck in a metal tube going 500+ mph at 30k ft. They don't have any agency over what happens. The industry combats this by having really, really tight regulations (well, they do until someone in the C-suite tries to fuck with it).

With a car, you're in control. There's a heavier emphasis on "personal responsibility". When the truck with a 5' hood hits a kid crossing the street, it's the kid's fault for not looking both ways. We have a bunch of stuff that tries to make things safer (mostly for the occupants), and a lot of it has made cars heavier, more expensive, and sometimes more dangerous for people outside the car.

This deserves a more in-depth writeup on the evolution of car safety equipment than I'm willing to do right now, but the conclusion should be that you can't make cars work as a primary mass transit method. We're over a century into cars being mass transit, and we haven't really solved it, because we can't.