Whenever I get a response to a job application (e.g. being asked into an interview), I ask whether developers (I'm a software developer) are permitted to choose their own operating system. A lot of the people who I've asked seem to think this is a strange question, and either don't have an answer or seem put off by it.
For me, I'm just not interested in working somewhere that will require me to use an operating system that I'm not comfortable with. I understand that there is a big benefit to having teams using the same software to ease collaboration, which is why I don't have a problem with being rejected based on my refusal to work with a non-Linux operating system.
For me, I'd rather have a job where I can work with the tools I prefer (like Linux) rather than take a higher-paying job where I'm required to use different tools.
That's a personal decision and I'm quite comfortable with it. I don't mind sacrificing money for comfort. The question is, though, how do I communicate that to potential employers? I'm not trying to get them to make exceptions, I just want to make sure they're going to be ok with my choice before I waste both of our time with an interview.
For context, the work I do doesn't lend itself to one operating system over another; it's not like I'm applying for a position as a .NET developer, where Linux really doesn't make sense. The kind of work I do can be done on pretty much any operating system, I just prefer to stick with the one I've been using for the past 15 years.