Well, some years ago I helped a friend move from a place in central Amsterdam to Berlin. It would have been really expensive to hire a moving company, compared to renting a van and a car.

In Berlin, where I live (in the center in fact), we're big on reusing and recycling. I don't own a car, but quite often I need to transport bulky second hand items from wherever I bought them, or bulky trash to the recycling center. So I drive one from a car-sharing app.

I've also needed to take someone to a hospital, and it was just quicker to grab a car2go than waiting for an ambulance.

My point is, there are many use cases where the ability to drive or call a taxi is better than the existing alternatives. I agree that cities everywhere need far fewer cars in them, and I think Berlin with its focus on biking and public transportation but availability or car-sharing vehicles for on-demand private driving is heading in the right direction without having to outright ban cars.