I'm guessing here: The guys installing those arguably very simple IT-systems mostly couldn't bother with Linux. Add to that, (at least here in Germany) BK is a

I'm guessing here: The guys installing those arguably very simple IT-systems mostly couldn't bother with Linux. Add to that, (at least here in Germany) BK is a franchise that sells licenses to franchise operators, so I doubt they have strict requirements on the actual IT setup, just the pictures they need to display. So you have very normal, run-off-the-mill managers and IT services, the former unable to grasp that Windows 10 with constant updates and fuck-ups will constantly require the services of the IT guys, and the latter naturally profiting of that. The increased margin of not using Windows wouldn't be enough to compensate that, and an increased price for a Linux package is something very difficult to convince those managers of. And then also IT-people well versed in Linux usually have clients who pay substantially more than simply outfitting non-IT businesses with IT-equipment.