As far "car free" high streets, plenty of vibrant town centres are car friendly and remain very popular because they have sensibly sized/priced car parks and no stupid traffic calming and one way systems causing gridlock. People can still drive to them and park easily/cheaply.
Thing is, if I am a "car person" ("I like cars, I live in the suburbs because I want space to park two cars and have a car for every adult in the family, I prefer to drive everywhere, don't want to use public transport, would never considering cycling, want to patronize places that welcome me and my car(s) and make it easy for me to drive in, drive out and park in the meantime"), why would I pick a city center -no matter how car-friendly - over an out-of-town shopping centre or out-of-town shopping park filled with great big box-like shops?
Because no city centre is ever, ever going to compete with those out-of-town retail developments on car-friendliness.
The out-of-town retail places always have far more places to park free of charge and are approached by great big spacious roads; it's so easy to drive there and back and find a parking space. And then, once you are there and parked, you have these great big indoor spaces to wander around freely with no cars fouling up the air or making you panic for your toddler's safety.
A city center or high street, even when designed around cars and trying to compete with the out-of-town shopping mall, is fighting a losing battle. It just inherently does not have a car-friendly structure due to the lack of space, narrower roads; even if you blanketed the whole bloody place with free parking slots, it still won't have as much free parking as the out-of-town shopping mall. And then there isn't a nice indoor spacious car-free, fume-free area to wander about from in safety from the cars. You're stuck there with all the cars and spend most of the time dodging them and breathing in their fumes. Fun times. Why would anyone bother with this when they could just drive to SunnyLakes Shopping Haven out there in the surrounding countryside?
As suggested above, build city centres full of housing and let urban types (who actually enjoy cities, unlike the professed "car people") have their low-car cities on their doorsteps. It does seem to work just fine in other countries?
If you are a "car person" and you feel angry about city centres/high streets that are hard to access by car, well, don't go there, then. Just stick with your suburbs and drive to out-of-town retail developments/shopping centres when you want to buy something, have a day out, eat out or go to the cinema. There are plenty of these places and they are not going anywhere.