For most people it's not about the supermarket. Those are a dime a dozen and all the same. It's easy to provide those in sufficient amounts everywhere.
Now try it with jobs. Not any job, but your job. Is it possible to have your job be 5 minutes from your home. How about in 5 years when your job is underpaid or unfulfilling? Is your next job also 5 minutes away? Or do you now have to move? And 5 years after that, when you're laid off?
I find that loads of people start out enjoying the car-free experience. And then they get a job in the next town. And/or they get kids, so commute-time takes away from kids-time. Life becomes too busy to spend the extra 30 minutes commuting per day that public transport would cost.
Between the trade-off bad job, no time, and car/public transport, the car quickly becomes the best solution. Even if you don't like driving.