If you are talking about a city where this makes sense like Phoenix, the public transportation is very poor. It can take 90 minutes to cover the distance you could drive in 20.

They have a light rail, but it only goes between downtown and a few suburbs. Your other option is several bus transfers.

If you’re thinking of cities like New York or London, public transport is more practical in many cases.

Not to mention how hostile Phoenix can be to walking.