Being able to live car free is pretty much limited to (expensive) major cities and some (expensive) mid-sized college towns.
The city of about 50,000 I'm from not only has no public transit and limited sidewalks, it doesn't even have crosswalks across the two main 6-lane roads that divide the city, so you can't safely walk more than about a mile even if you wanted to.
I live in the UK (hardly a bastion of public transport) in a town of under 10k, and have a car. The main requirement for a car is to take my youngest to Drama club in the next town where it finishes at 9pm, well after buses have stopped. There is a drama club in the town, but as we only just moved we didn't want to move him. Likewise we're driving him to his old school until the end of July as he'll move school then.
I used to live in a village of 300 people, and sure you need a car there.
Sure it was nice to drive the 4 miles to the garden centre at the weekend rather than take the hourly bus, but it's not a requirement.
For a town of 10,000 people, let alone 50,000, to say you can't live car free is nonsense.
Of course America is different. Their towns are far less dense, they don't even have "sidewalks", they are consciously built so you have to drive everywhere, but that's unique to the time American towns were built.
So again, what towns in Europe with a population of 50,000 have no public transport.
And the other 55% may have access but often it doesn't meet people's needs (it may not go when/where they need to go)
Only 11% of Americans use public transit at all on a weekly basis.
3.5% of Americans use public transit to commute.
I live in a well populated East Coast state, so it's not like I'm even really far out in the sticks too, there are many places which are even worse off in these regards.