[legion]

Here's another thought.

New cars are not selling right now. A LOT of people are buying used to save money. So much so, that used car prices have doubled or more. I can confirm this both by anecdotal evidence and by news articles.

The trade-in gave them a much-needed used car to sell, and got a new car off of the lot. Because the used car is worth so much more now (2-4 times as much as a year ago), they are willing to make what would normally seem like a crazy deal.

This is one of those rare situations where there is no catch, and everyone wins.