Sounds nice if you live in a good climate. Doesn't work when you have freezing winter temperatures or broiling summer heat.
For example, a public transportation effort here in Austin has been largely a failure because a bus/tram/blight rail/etc. rarely takes you exactly where you need to go and you are forced to hoof it several blocks in 95-degree heat to get where you intended, often dripping in sweat.
The socialists have thrown all sorts of money and environutsy ideas at the problem but you just aren't going to talk most people out of their air conditioned cars in July.
And up north the sidewalks ice over.
A personal commuter device (like a car) means climate control and keeps you from having to associate with x number of strangers with communicable diseases.