Wheelchair work is usually a non-profitable job fer a Taxi driver, I have done it in the past when I was renting an 8 seater WAT. Firstly the wheelchair jobs are handed out by the base to the driver 30 or 40 minutes in advance of the job meaning that you have to wait that lenght of time before pick-up. Then you have to 'load up' which takes about 5 minutes before the meter starts, (I know it should start on arrival but you would want to be proper nasty to do that on a wheelchair user) and then the meter stops at journey end, take payment, often less than a Tenner, and then another 5 minutes to 'unload'.
I have every sympathy fer those confined to wheelchairs, but fer a Taxi driver trying to make a living they are non-profit jobs, and to add and I have had a few in my time, quite a lot (not all) of wheelchair users are highly obnoxious spoilt brats who think the world should revolve around them.