http://www.bbc.co.uk/news/uk-39138775
Having worked with people with learning difficulties and even employed a few within my department I can say that on the one hand they are an asset. Usually cheerful and willing and dedicated to doing their best.
On the other they all without exception were only able to do about 30% to 50% of the work of the rest of the team were expected to do.
There were members of the team, while welcoming them as a part of the team and getting on with them as they would any other, did still resent the fact they were carrying them work wise but were all still being paid the same.
I know my experiences are probably limited and not diverse enough to sweep all into the same category but my thought would be the employer pays the rate at which they work and the rest, to bring their pay up to the going rate for the job or minimum wage, would be subsidised by the government.