Yea the developers are most likely hourly workers, maybe some salaried. They already got paid.

They do. But they have a version for pretty much every holiday.

They tried that at one of my jobs as well. A bunch of us refused to install it on our personal phones. Management started floating the idea of getting work phones for those people. Came in and asked how many of us would like a work phone instead of installing the app on our phones. They were not prepared for how many of us raised our hands. Never heard anything about it again.