When I ordered my last Motability car, the dealer explained that although they don’t make a loss on Motability sales, the incentive is that each vehicle counts as a sale. This means the dealship gets larger discounts on the cars they sell to private buyers.
These discounts are huge. My dad worked at a small dealership and it cost them less to buy from a large chain dealership than to buy direct from Vauxhaul. That’s how large the discounts can be. Obviously, the small family run dealership couldn’t compete and had to close.
With lack of availability, I don’t think manufacturers will be offering dealerships huge discounts, hence another reason dealerships don’t need Motability for these buying discounts.