A lot of developers pay for their IDE (PHPStorm, for example). And a lot of software accept donations. I don't think people think money is evil, but to accept it, you need to be able to receive it, and that might be too much overhead for a lot of people.

Also, Mac is a much bigger market than Linux on the desktop, and tends to be used by people with money (for the expensive hardware). More of a profession, less of a hobby.