They're far enough away that it doesn't make sense to put off purchasing normal buses (which could probably be retrofitted with self-driving tech anyway). And certainly that doesn't obviate the value of things like planning and beginning to carry people on routes; setting up stops (signs or shelters); and setting up bus lanes.

And rail transit is a whole other beast. Do you know how much higher a volume of people can be carried by a subway than by even the most efficient bus route running buses bumper-to-bumper (let alone private vehicles)? (The unwillingness of politicians to acknowledge this is one of the reasons the L train shutdown in Brooklyn next year is going to be such a shit show.)

Is there a metric where they’re not worse at what you’re suggesting than trains?

Cost and flexibility. Buses are cheaper and more responsive to changing traffic patterns than trains. They are not as nice though.

If for instance people in a given community want to start traveling to a different part of a city they either have to create new rail routes or people have to take long inconvenient trips.

> They are not as nice though.

Ha! Apparently you haven't used Northern in the UK. Nice! (chuckle)

I don't think it's really about nicety, but about capacity.

A subway train can carry up to 1'000 passengers, depending on length and construction. You can have frequencies of a train every 90 seconds (example: line C in Prague, during rush hour). So you can transport up to 40'000 people per hour in each direction.

Buses, while certainly much better than private vehicles, can never match that capacity. Alas, they're much cheaper and certainly more flexible.

> Buses are cheaper and more responsive to changing traffic patterns than trains

True, but not very useful. The #1 Bus line in Boston takes a route that a trolley once took. And before that it was a horse drawn railcar. And before that it was a 10 seat omnibus carriage route. Same route for a mighty long time.

The flip side is that they’re on the same roads as cars, which means exposed to the same congestion. And to the degree they get some people out of cars, they get other people into them.

For better or worse, trains have fixed routes and aren't very dynamic. I actually find it a bit surprising we don't see more of a formalized mini-bus system in the US given that it was pretty popular in some other countries even before GPS and apps. I guess UberPool serves a somewhat similar purpose.

Perhaps there's not a lot of overlap between people who take Uber a lot and people who willingly step into a bus of any kind.

In the US, the bus is generally seen as a "poor-person's" transport. Trains are considered middle-class transport.

Going doorstep to doorstep and probably lower time for the overall trip.