[reidacdc]

We had something like this in the exurbs of Calgary in the 1970s, it was called "DART", for "Dial-A-Ride Transit".

It was semi-on-demand, and not door-to-door.

The scheme was, you called the DART line (from your land-line, obviously) and gave your address, and there was a mini-bus that made the rounds of the residential neighborhood, which would come to your address on its next round. It would then take you to the local transit junction point, a nearby shopping mall with several bus bays where a number of regular bus routes converged, and you would make your connection and complete your journey in the regular way.

It seemed to me to be a reasonable way of efficiently delivering infrequent transit service to a large area, although I personally only used it a couple of times to visiit a friend.

[jmpman]

I’ve imagined that self driving cars would fill in this “last mile” from the end destination to an air conditioned transit hub. Once you get enough density in a transit hub, the frequency and destinations should explode, making the network usable, even in car heavy towns like Houston.

[bluGill]

I don't see how. Once you have a car you may as well drive all the way there, and self driving makes it much faster. Then you have the convenience of the car when you get there. either way you need a parking lot for the car to sit in.

Transit works best when you can get rid of a car. The cost of owning a car is very high, transit good enough that you would get rid of a car is only a little cheaper. Bad transit is only a little cheaper, but most people will just use their car. Note that I said a car: most people are in a family situation with more than one car (or at least more than one person who could get a car if they wanted one), so we can save money by having them get rid of one car and the other car is only used for those 5% tasks that transit isn't good for.

[ceejayoz]

The self-driving cars in the parent poster's comment wouldn't be personally owned. They'd pick you up, drop you off, and then go get the next person. It wouldn't be doing much sitting in parking lots at busy times, and could park in municipal lots out of the busy areas at night.