Remembering the first time this was aired, I found myself in the strange position of supporting Ryanair. I believe that it is the airports duty to get the passengers to the aircraft whether it's by 'bus, on foot or in a wheelchair.
No airport seems to have direct access to the gates, they all take you on a voyage of discovery that is in reality, a glorified shopping opportunity from which they benefit.
There are those who flagrantly abuse the wheelchair system. Perhaps the Blue badge parking scheme could be used to identify the disabled.
Those that do qualify should certainly receive every help, but expecting the airline to supply a ticket for £30 and throw in a free wheelchair at each end is being a bit unrealistic. It should come out of the airport budget as they have often created the need for transportation.