People are paid less when they are younger.
I don't know whether it's in recognition of them still being supported by parents, or whether they bring less to a role. 🤷🏼♀️
It depends how you see 'work'. If an activity is not productive, if it does not create some value/wealth, then should it be paid as work?
How would you keep a business viable, if you pay people who cannot work unaided and unsupervised at the same rate as people who can?
I understand your outrage at the flat statement, 'people with learning disabilities should be paid less'. But how will you keep people with learning disabilities in work, if they are competing with people without learning disabilities?
If people are receiving benefits and assisted care in recognition of the fact that they are unable to earn their living, why would they also be paid at a rate that allows them to earn their living? That doesn't make sense!