Roz, you use the most extreme of instances to back up your points, when others could easily use a lightweight buggy when it's appropriate to do so for the child.

Yes, instances of buggy folding taking too much time and the driver going off even happened in the good old days, but yet in that era, parents were expected to fold them up regardless and nothing has changed now except for the fact that buggy designs have changed where it's easier for the parent to wheel their kids and shopping and buses are now low floor so that the need to fold the chair has been reduced to the extent that parents expect to be able to wheel them on the bus and into the wheelchair area.

No-one is suggesting you and Jane2 shouldn't go out and use public transport with your buggies, but then don't complain when a wheelchair user requires the space you're using as they have under TfL guidelines, first use of the area.