Put simply flying cars are horrible. Dangerous projectiles piloted by idiots or untrusted AI guzzling fuel and/or electricity and an absolute FAA nightmare.
You think drunk drivers are bad? Wait till you get drunk flyers hitting your house at 200+ mph and wiping out the extended family.
Could probably program them to pop onto "rails". Will never happen until we got a real robust power source. I think bitcoin miners might punt on cold fusion, that'll shake things up.