To me it is perfectly obvious, it is because Windows is the default and has been for a long time. It is what people know and what people fall to when put on the spot to do something. It offers security, you don't have to venture out of your comfort zone. It offers ease, it just works enough the first time and long term issues can be ignored since the bill was paid. Of course that you have to reboot it every so often, or invent some device to keep the mouse moving doesn't matter and make the people using feel ever so smarter. That is what I have seen in the last 10 years working in the IT field.
But this is changing Windows is no longer the default for everything, more and more people are discovering alternatives like a Raspberry PI running Linux. The shift has started and will only pick up speed.