Indeed. It depends what you're doing. Web development, yes, I can see why you'd want a UNIXy system for that. But a lot of the enterprise is Windows-first and if you want a desktop app, that's what you'd develop on. If you're doing embedded development you may have a choice of exactly one operating system with the manufacturer's toolchain.

Do not underestimate the power of full Visual Studio. It's a bit bloated, and it's even slower with Resharper, but if you're working in C# it will do a lot for you.

I've found the opposite - with the companies I've worked for (all Australian) in the past 10 years, there's been a total of 5 developers I know of who ran Windows (and that's including a person who used to work at Microsoft).

Swiss here, in my work experience only part of the management used windows.

I also know some small shops enforcing it, but I don't know any dev who uses it because he wants to.

As an observation, especially in the 3rd world, and "3rd tier business" I think Windows is the dominant operating system.

Which some are still running XP. These are the places that could benefit the most from Linux or BSD to keep that hardware running as long as possible.