I am willing to bet that it is costing Tesla a lot of money to have their Traded in Used Cars sit right now. If a new car is only 3 to 5k more than a used one people are going to purchase new cars. The cars that Tesla took in on trade a few months ago are worth less now. Tesla has too much money into them and those cars are competing with cars that Tesla paid less for on trade in during the past few weeks. The older cars will keep loosing value until Tesla sells them at a break even point or at a loss.
they gave/give really low prices for trade in. What you're saying applies to the likes of Carvana etc. Lots of threads about low prices for TSLA trade in.