Can you expound on this claim? At least where I live it's almost impossible to live without a car. Though just this month Walmart did start doing delivery from 20 miles away.
There are people for whom it holds true, and then there are people for whom it doesn't. The reasons are many and varied, but some of them are deliberate. Most of us live in or near cities. If we need cars it's because those areas were designed around the car. America was unique in this until recently because of its young age. Most of our nation wasn't built up until after the invention of the automobile, so we had the opportunity to do that. We built on a larger scale (with larger zones, blocks, etc) because we were designing cities on the scale of the car, not the human.
People think the car allows them to go where they want, when they want, and that seems true until you realize that your average car is completely worthless the second it gets even a few yards off of a road, and roads themselves can be compromised in a whole bunch of ways. People who are sure that their cars will serve them in an emergency, for example, are ignoring that the gas pumps run on electricity and the largest, widest roads can easily be clogged by just one or two incidents. In inclement weather, you can run out of fuel just trying to stay warm or cool while waiting for the road to be cleared.
It's terrible to live where I live (Humboldt county, CA) without a car, but there is a rail line running right through the county. Unfortunately it's abandoned and overgrown, and it would cost billions upon billions to reactivate it now for light rail. I live in a not-particularly-remote part of the county (this city is only ten minutes from a better served city) and the bus only comes here every other hour. But I can see the rail line from my back yard! Thankfully, I am able to work remote four days, which saves me almost $300/mo in fuel alone and I drive an econobox.
Could we replace cars with rail for everyone immediately? Of course not. They will continue to make sense for rural residents for the foreseeable future. But for everyone else, it makes a lot more sense to do rail for long parts of trips and shuttles or even smaller vehicles for the last mile, especially when self-driving tech gets up to par. The cars have their place, but we don't need as many of them, they don't need to be as large and long range for most users, and we don't need to be designing our entire culture around them. It should be the reverse.