They work better in Linux than Windows, not to mention backwards compatibility.
EDIT: I may be wrong about newest printer models, 2020 and above.
EDIT2: Hardware problems are an entirely different issue.
It’s no surprise Apple uses CUPS. They wrote it, after all.
Edit: TIL Apple didn’t write CUPS themselves but they bought the company that did it pretty early in the game. Here’s a LWN article from the time, exposing some of the worries that came with the news of the acquisition: https://lwn.net/Articles/242020/