How does the Used Plane market Work?

In Otto I have noticed that a lot of planes now have 0 used planes on the market and its random like no 787 but a few of 777 available or no 320/321 but there’s still 737-800 and 900’s to me it just seems random and they are not all from returned leases.

hey there! i know that i added a bunch of used models of each aircraft type that is still available from the manufacturer for the server launch, maybe some of them have just sold out?

787 is a popular plane, 777 is not. That can be an explanation.