In California, at one point, you could get a few thousand rebate, if you were in the Central Valley, and additional few thousand rebate. Some local cities gave rebates on top of that, and the federal tax rebate on that. Buy a $45k Model 3 and get back $13k-$15k just for buying it. Rebates like that are going to play havoc with resale values. On top of that, new Tesla's went down in price over the past several years. I think as these incentives taper off we'll see more of a stable drop off.

I think buyers just understand the value of a battery that they've cared for and babied compared to a battery with unknown history.