Car=freedom in this country. People ain't giving up their freedom. Very few people will accept being forced into mass transit shared with alcoholics, drug addicts, schizophrenics, and criminals. If you want mass transit to succeed it has to provide the same freedom as the car and a similar safe and clean environment. Remember, people vote for bond issues and other tax increases for mass transit in the hopes that their neighbors will take it and free up space on the roads for them. Not because they have any real intention of using it themselves.
A lot of folks see a car as freedom, but a lot of others see a car as a ball and chain. A lot of people would probably give up their cars if mass transit projects were given the resources and attention that large freeway projects are given. A lot more would give up their cars if they had to pay the true cost of driving. I think attitudes are shifting, and the day may come where drivers will be told to pay their fair share.
This is all probably very location-dependent. I mean, car = freedom only in specific places, and because of how many cities started and grew. There are dense cities, and even suburbs and small cities, that are better for mass transit and bicycling than owning a car. Anyone who ever has to drive in the vicinity of LA, is that freedom, really?
In a related vein, we recently returned from a vacation to Denmark. Car is definitely not freedom there. Plenty of bicycling and mass transit and rented standing scooters. We rented a car because we had a lot of plans all over, but it was pretty much a PITA half of the time. Find parking in flat #1, figure out how to navigate the app, figure out what the rates are (learn eventually that rates in front of the flat are 2x rates 3 blocks away). Near the city center, even more expensive. Except Sundays are free which means: good luck finding any spot! Flat #2 came with an underground parking spot that took a 15 point turn to get in and out of (thanks to that "free upgrade" to a small SUV.) The vast majority of parking spots in this building were occupied by bicycles and even a ping pong table. 1 in 5 actually had a car parked there.
The infrastructure was great for bicycles in Copenhagen and even elsewhere on Zealand and Jutland. Most places had a dedicated bike path with their own traffic signal. I was impressed with the number of women biking in dresses and skirts, to be honest.
Obviously they put a lot of money into mass transit, and they make owning a car very expensive. I believe our friends said sales tax on a car is ~80% when you buy it (which is why most cars are small). Then there's the gas cost, roughly 2x what it is here in CA ($11/liter). I don't know what bus/ train tickets cost (we got one 24-hour pass that included entrance to some sites). Even car rentals are expensive - the Danes were surprised at our rental car rate for 2 weeks - but if they were to rent a car, they would have to pay tax, and we don't. Also, parking is not free. In Copenhagen, cost depends on zones. To go to any sight - Legoland or other amusement parks or even a public park/ coastline for a hike - you pay (also: no cash, cards only, pay at a kiosk). The only free parking we had was when visiting friends at their homes /summer houses.
I loved it, esp the walking (we didn't bike bc youngest kid doesn't do that yet). And admittedly, I'm not a car person - but my matrix is actually bigger than most cars we saw on the road. However, America's "car culture" might take a nosedive if suddenly your $28k car costs you $52k instead. There are places here where cars make sense (I grew up in the middle of nowhere - a 20 mile drive to the grocery store), and places that they don't (NYC anyone?) We had family from there visiting us recently and the first question was "doesn't anyone bike here? It seems like people drive literally everywhere?" Pretty much.