There are two fair options that are available. The first one (in my opinion the better one) is keep the system as it is, and allow anyone with any disability to have a disabled persons railcard. The other (in my opinion not so good, but it would still be fair) would be to withdraw the disabled persons railcard altogether and charge people the same fare for the same journey whether they are disabled or not.
Your second option, as I understand it, would simply align the treatment of disabled travellers with those who aren’t disabled. This would certainly be
consistent but I’m not sure it would be
fair given that they aren’t starting from a level playing field. The disabled (whatever their disability) generally have a much tougher time of it in day to day life generally.
As a civilised society, im sure you’ll agree we should be helping those with disabilities where possible. Boosting their ability to live independently and have access to education and jobs via discounted travel is a key part of this.