Lack of inventory, high demand...up go the prices. The used car market is starting to show signs of stabilizing a bit, and come down gently, but not drastically yet.
Yet another reason why so many manufacturer banks (if they hadn't already) put locks on their lease buyouts (Honda, GM, Ford, Kia, Mercedes, BMW, etc.) so people would stop dumping their leases early at Carmax/Carvana/etc. and cashing out with an equity check--and those cars not making it back to the originating dealers, to sell again as CPO. Sucks if you need to get out of one, but many manufacturers are shoving some new rules in place where they can.
New car addendums is a tough one to have any say in though, as "they are independent businesses" by the rulebook, but manufacturers try to fight it from a different angle by picking apart their poor customer surveys, reviews, etc. when they over charge or are rough to deal with, and go in that way--customer satisfaction scores actually take more precedent, in many ways.