I don't think that you can meaningfully discuss public transit in the abstract. What works in one city won't necessarily work in another, with the density of the city being a critical factor. You also can't hand wave away the tremendously expensive upfront cost of something like light rail.
And, as far as I can tell, public transportation is only really successful where driving (including parking) is particularly inconvenient.
It takes me 25 minutes to drive to work. If I take the bus, (which is convenient to my house, and runs twice per hour) it takes me 40 minutes; cost is $1.75 one way. (Biking takes 50 minutes).
So the value proposition isn't that great, it takes more time, and it's less flexible if I want to stay after work or do errands on the way home.
Note, too, that if I miss the 7:30 bus, I could drive to work before the next bus arrives (and the schedule creates its own inefficiencies - if I'm ready to leave at 7:15, I can't; I still have to wait until 7:30).
And our bus system is very much of a hub-and-spoke design: good for getting to and from work, particularly if you work downtown, but not necessarily good for going across town or visiting anyone who doesn't live downtown or on the same spoke.
I think that these factors, more than anything else, tend to mitigate against greater public acceptance of public transportation in a lot of newer cities.
Later this year, my city is rolling out an electric car share service, which I'm looking forward to. Unfortunately, they haven't set the price yet; but it may provide a better model for non-dense midsized cities.