The problem is that it's a classic large-scale prisoner's dilemma. Living in a walking city is nicer than living in a driving city. But living in a walking city with a car is even nicer!
The only way to fix it is by passing taxes or other restrictive legislation, which has so far been extremely difficult because most voters choose "let's make things a bit easier for you today" over "we should all sacrifice now to make things probably better later".
The only way to fix it is by passing taxes or other restrictive legislation, which has so far been extremely difficult because most voters choose "let's make things a bit easier for you today" over "we should all sacrifice now to make things probably better later".