The only problem with competition rather than the Motability monopoly is if you equate it to the many independent corner food shops all having competition with each other, it does not bring the prices down below what the large supermarkets can charge/sell at, due to their buying power that the corner shops can’t compete with.
Arguably, rather than having Motability with it’s Monopoly and large buying power, you had 3 or more all competing, would they still have the large buying power to negotiate even lower prices from the Manufacturers and pass it on to us or are we just creating more tiers of competing bureaucracy as in the UK Government and the Scottish Government which both have to be paid for and are often duplicating each other.