Comment by cyberax
I ran the numbers, and for most non-braindead cities something like a fleet of 6-seater minivans will easily replace all of local transit.
And with just 6 people the overhead if an imperfect route and additional stops will be measured in minutes.
And of course, it's pretty easy to imagine an option to pay a bit more for a fully personal route.
This exists in a way -- I'd wager every city has a commercial service that will shuttle you to, say, the airport. They're not cheap, however.