Do you need a lot of legal hoops when your employee has just been straight up lying to you about their disability?
Would it not be unethical for the employer to advise you on your first day that, actually, the company is struggling and can only pay you 60% of the agreed wage?
There is a major risk to employers pretty much any western country when it comes to these sort of discrimination claims.
Also depending on the jurisdiction and circumstances they might say that they honestly believed that they would be capable of it but realized that they aren’t and you might be obligated to accommodate them to a certain degree.