If you're curious about the technical issues:
Writing software that works with a webcam on Windows requires an understanding of DirectX/DirectShow or MediaFoundation. Microsoft has been using a variant of this DirectX/DirectShow for the past 20 years and so people are VERY familiar with how to use this API. Until MediaFoundation completely replaces DirectShow, Windows is easy to program for in respect to webcam software.
That brings us to MacOS. To write webcam software for MacOS, either AVFoundation or CoreMediaIO needs to be used. They are both very poorly documented and the examples given in the documentation do not work without being edited (which would require you to already know the APIs). To make things even more difficult, these are currently being ported into Swift, which is intended to replace Objective-C as the primary app programming language. To put it simply, there are a lot more choices you have to make in designing webcam software for MacOS, and absolutely none of the options are appealing.
There are open-source options available as a workaround, but those come with their own issues and faults, and generally just do not work as well as the platform-specific options.
Edited to add an apology for answering a question in 'Ask-a-Model', given that I'm not a model...