> Cars are by far the least space-efficient method of transporting people
Not true in practice even if true in theory; in many places the average full-size bus contains fewer people than would fit in a minivan.
The problem is you need 5-10 years of reliable public transit in an area before non-transit users begin to convert (or transit users begin to move in).
If you myopically look at the instantaneous usage of infrastructure then you could argue that most roads are pointless because they are, on average, empty.
The bus might have less than 5 people on it at any given moment you observe, but over its >2 hour route it transports dozens or hundreds of people between stops.
Passenger-mile vs vehicle-mile is a useful metric (you can add driver-mile if you want, or cost-mile) but you can probably do something similar with some measurement of storage space, too.
A full minivan ranks surprisingly high on all of them, which is one of the reasons it's disappointing that carpooling and such aren't discussed as much anymore.
Or you can start with minivan buses, and switch to traditional one when minivans stopped being enough
In my city less common routes are still purely minivan because why not. Some seasonal routes (more relevant in summer|winter) are also partially or full minivan.
(sidenote: I'm pretty sure it started because few guys with minivans noticed that some areas were under-connected by buses and just started a business driving those routes back-and-forth on a schedule. Then some regulations were slapped on top. So it looks like public transport have tendency to spontaneously appear in denser areas)
In Mexico it was always a decision of "do I walk a bit further to get the jitney and pay a bit more, but likely go faster (it stops picking up passengers when full and just goes until the first drop-off), or do I get on a bus sooner for cheaper but likely slower?"
Not true in practice even if true in theory; in many places the average full-size bus contains fewer people than would fit in a minivan.
The problem is you need 5-10 years of reliable public transit in an area before non-transit users begin to convert (or transit users begin to move in).