I see a couple of instances where these might be viable:

Firstly, people living in larger multihousing complexes could subscribe to a door-to-door commuter service, for example to the west end of government row. Some households could then eliminate their commuter car and its implications. Others could avoid the mess of walk-bus-wait-transfer-bus-walk that they're stuck with because they live in an area with awkward public transit options.

Secondly, grocery chains could run periodic shuttles where an individual store is surrounded by high density neighborhoods By this i mean that a chain could run a bus at one store one day and another the next, etc.

I believe that this transportation option should be allowed in the General Plan.