XP was almighty popular for any sort of scientific instrumentation, in no small part because of its good compatibility with Windows 9x (!). Manufacturers of advanced equipment tend to worry about small things like Proper Science rather than OS versions and other hipster stuff, and they're often small companies, so they historically tend to go Minimum Effort Required when it comes to interfacing with computers. They're also very worried about performance, so they have to go low-level, increasing the likelihood of incompatibilities with the latest and greatest and reducing maintainability in general.

A lot of drivers were developed back in the '90s and just tweaked for compatibility when absolutely necessary. Long-term compatibility is also why that world tends to favour Microsoft, that's one thing Redmond really cares about.