This (mostly) isn't servers, but things like checkin kiosks, computers in hospitals, self-checkout screens, large displays that show departing flights etc.

A vast majority of those have historically been running on Windows, as they're essentially computers with a GUI, but running one specific app, and Windows GUI development and system administration is just what people had experience with. You could do Linux for sure, but desktop Linux is notoriously brittle.

New appliances like these aren't always Windows any more, some places use Android, some places use Linux, some places even do iPads, there's a much wider variety, but there's still plenty of Windows left.