Eh ? You're not grasping that there is a link between between reincarnation and prejudice against the disabled. What are we supposed to do, just ignore the connection on the grounds that there are other forms of prejudice with other roots in other places. Where we can identify the causes of harm we can do things about it, and this might mean in the long term campaigning to change attitudes through better education. People trapped in a twin cycle of poverty and disability are among the poorest of the poor and the discrimination they suffer will not go away by some glib hand waving exercise pretending that the problem does not exist.
What?! I am saying that there is no connection between reincarnation and prejudice. You are just imagining it based on some experience in Laos and Cambodia or whatever. I remember, Hope who is a Christian, had a similar impression based on the few years he had spent in Nepal. He believed (I think) that Christians had a more empathetic view of everyone compared to Hindus. Many westerners have this (rather superior) attitude of understanding the East and its prejudices just because they spend a few years there. LOL!
Also, correlation is not causation. No one has established any such connection especially in India, which has the largest population of believers in reincarnation. You just like to believe all that because it suits your stand.
Prejudice is present in all communities, more so in communities that do not believe in reincarnation. Any belief in God's wisdom or fate can bring about prejudice against the unfortunate. In fact, even simple 'bad luck' can be used as a reason for prejudice. It all depends on how empathetic or other wise the individual person is....and that has nothing to do with reincarnation.
Changing attitudes in India favouring the disabled is not happening because of rejection of reincarnation. More and more youngsters are now taking to Yogic philosophies of reincarnation and karma. They are also however becoming more helpful and socially aware. It probably has something to do with wealth, technology, facilities, communication and such things.