How are you verifying this in job interviews? Not using Windows is at the top of my list of wants in a new job, to me it'd be as good as a $10k raise. But I'm aware that asking about this during an interview sounds petty.
Or otherwise make it a gentle enquiry, "I see you provide laptops, can I get a linux/Mac machine to work on?"
Framing is key ;)
Edit: personally I outright asked "can I choose my own OS, I can't deal with windows, it makes my head hurt" or something like that. If you have the confidence just tell em how it is.