You misunderstand slightly - I didn't mean to infer that disabled people are a burden to the railways - far from it. We are very very capable of carrying wheelchairs and guiding blind people etc. at a moment's notice.
I refer instead to the thankfully small but vocal percentage of people who expect the railway to act as their own personal chauffeur / taxi / portering service, calling upon resources that in some cases simply do not exist. I accept able-bodied people do this too - people expecting me to monitor their luggage for example or to hold the train while they have a cigarette! - but for disabled people to cry "discrimination" when situations do not necessarily present themselves as they would like is, unfortunately, unacceptable. Being disabled does not automatically equate to absolving oneself of any responsibility for one's circumstances. The world is regretfully not 100% disability friendly and as such a little leeway on both sides of the coin is required.
Coming back to the original point, I would say this : We can accommodate, we can provide access where possible, and we can do what we can where we can how we can. But we cannot and will not break, bend or distort any rule or procedure which will cause disruption or, more seriously, be unsafe to us, passengers or to infrastructure. If a train cannot carry a mobility scooter, it cannot carry a mobility scooter, even if the story is sold to the Daily Mail.