I have no firm knowledge either way, so am not taking sides, but if dealerships have sales people who do nothing but Motability orders that seems like a crazy business model to me. They must go whole days without a single Motability customer and certainly wouldn’t have enough to deal with them back to back all the time that they are working.
I had always thought that most dealerships have a Motability Specialist, but that just meant that they have had bespoke training and will be the usual ‘go to’ person for Motability customers, but they would also deal with other customers, just as other sales people can also deal with Motability customers. Our local BMW dealer has a Motability Specialist (maybe several) but we ordered through a sales rep that I already knew from when I bought a BMW privately. If another salesperson there only dealt with Motability customers then I would have thought that they should have insisted that we use them.