The reason that you see a difference between the different manufacturers is that that for some franchises Motability orders count towards their quarterly target AND they earn a volume bonus from the order, for others Motability orders count towards their quarterly target but they DON’T receive any volume bonus money from the order, and finally others don’t count towards VN or pay and are totally separate.
I think most manufacturers fall into the final category so they only receive a fixed amount for the initial deal and then servicing which can go down if they don’t hit certain standards.