I think they cost money because people put time and effort into making them, and being an alive human costs money. That + macOS users tend to be happy to spend a small amount of money to make their life easier
And that's totally fair, but this app is honestly rather trivial.. I think the surprising thing is that there are fewer Mac devs spending time making free software. I don't think Apple makes things better either by forcing devs to pay for a dev account to sell signed apps through official channels.
Exactly. I really don't mind paying for apps in general, but with macOS even those tiny trivial utils are mostly not open source / free. I'm talking stuff like changing mouse acceleration, add a "new xxx file" right click menu to finder or closing apps in mission control. Compared to Linux (and even Windows) I really miss some sort of open source movement.