I can't speak for every driver of course - there are good and bad in every profession - but, in my experience, a wheelchair user (powered or not) will know themselves if they need to use the ramp. In fact some will request the ramp when they don't really need it, but we as drivers will oblige anyway - imagine the fuss if we refused!!
The majority of bus stops (specially town centre) are raised so that when the driver "kneels" the bus, it is more or less level with the kerb. Usually powered wheelchair users without a carer know what their requirements in terms of assistance from the bus driver. However, unpowered wheelchair users accompanied by someone else tend to assess the situation for themselves.
I can't comprehend the fact that this powered wheelchair you refer to, was moving around when the bus was cornering. They must have a braking system on them surely - lets face it, if there wasn't one, and the batteries failed, there would be a runaway wheelchair - not good for the occupier, or who they crash in to.
There are even now some electric buggies allowed on buses (based on size - not the "road worthy" ones with headlights), but the user has to pass an instruction course on using the bus, and is issud with a card once they have passed. They then have to produce this card every time they get on the bus. As yet, I have not had one of these - I think the front end of the bus is complicated enough with baby buggies competing for space, as well as wheelchairs - and now electric buggies.
One thing worries me - despite the courses I have been on - no one seems to be able to clarify the the position regarding who has priority regarding baby buggies and wheelchair users. I can remember being told on one of the first courses I attended 4-5 yrs ago that under the DDA act, wheelchair users have priority over baby buggies. In other words, if you have a baby buggy occupying a wheelchair space and a wheelchair user wants to board (assuming there is no where else for the baby buggy to be relocated because of other buggies being carried) the wheelchair user has priority. So you then have to tell the person with the buggy to take the baby out and fold up the buggy, stow it safely, to allow the wheelchair access.Or if they are not prepared to do that, they should be politely asked to exit the bus in order to allow wheelchair access. Luckily, I've not had to deal with this one, and on later courses the goalposts moved until it became a sort of "don't know, I'll get back to you on this one"
Still unclear.
Isn't red tape amazin!!
I think I may have to re-visit the DDA and have a read - and then a lie down