Many companies believe the reasons why Linux users choose Linux instead of OSX (or even Windows) is because it's free and doesn't want to spend money on operating systems nor software.
But the reason can also be to get an stable open source system, non monopolistic and able to work in any computer.
Happily more clever companies do produce software for Linux (and Unix). Products such as Siemens NX, Catia, Nuke and many other very specialized and expensive ones work perfectly well with Linux and their users prefer that OS.