Robert Woolley wrote:

(a low frequency scheduled paratransit service).

It is low frequency (typically only two journeys, only 1 day per week)
and it is scheduled, but is it paratransit?

I thought "paratransit" referred to the (council operated) Dial-A-Ride
schemes.

I've used the phrase in this context as Mobility Buses have such low
frequencies and used specialised vehicles.

Not that specialised - I've known them to be used on normal buses
occasionally.

Don't forget that there is a progressive introduction of mainstream
bus routes in deeply residential areas....

They're not progressing with it very quickly - it will take a long time
to get them everywhere the mobility buses go.