School buses are a niche where everyone is buying about the amount of the same product from the same manufactures. You don't really get bulk discounts other than the same discount everyone else gets.

I don't think anyone buys them, period. They lease them. When the lease is up, they are re-leased or maybe sold to second-hand leasing companies or second-tier airlines, and ultimately they end up as freighters or scrapped.

The last of the DC-10s/MD-11s only recently ended service with FedEx. They may actually still be flying some MD-11s.

Buying is fairly common; Indigo just placed the largest ever single purchase of airplanes (500) https://www.reuters.com/business/aerospace-defense/airbus-wi...

If you’re leasing it’s not for free, the lessor is charging you a premium to make a profit over what they’re spending, so it still makes sense to own, particularly for large, heavily utilized fleets that don’t scale down much.