It's probably Windows IOT which is commonly used for signage and displays

https://en.m.wikipedia.org/wiki/Windows_IoT

That's not the case. Usually governments and public organisations go throw a volume licensing agreements that sees them taking more than just windows. It would usually include things like windows, office, a bunch of enterprise applications, as well as support on top of it all.

Microsoft usually relies on those agreements to push software that might not be needed.

Another reason could be the video display management system they used to remotely control these screens. The software might only run on windows.

This seems rather harmless. In the past people have been posting photos of Windows running on ATM cash machines 🫣

If they only have a support team for Windows, then it makes sense to use Windows only for all their devices. If they deploy a different OS, then they need to either hire a new support team, or train the existing team for the new OS. Either way would be more expensive than the licensing fees.

The intern who did it didn't know better and it's cheaper to spend hundred of thousands on Microsoft rather than project past the next few years since whoever is in charge will be gone by then.

Welcome to the work world, where inefficiency is only problematic when it shows up on an Excel sheet.

Linux is not always the answer, and free to install isn’t always cheap.

Imagine if the bus had a 4090 running that display

Worked for 2 digital advertising companies and the cost of Volume License windows is nothing compared to the cost of the rest of the hardware.

We were paying AU$700 for a Lenovo PC and another AU$800 on a screen while the volume key for windows was less AU$100.

Why save AU$100 per pc when I have to spend several thousand more per year paying some to run a remote Linux box rather than a windows one.

At Kuala Lumpa International Airport half the signs were like this near our gate a couple weeks ago...

Linux isn't free at the enterprise level. You aren't just downloading a Linux flavor and slapping it on everything. There's going to be a support contract to cover if something weird happens an expert is on site to help fix it within 24hrs. There's going to be guarantees that if software does x it will work even with future os updates. Replacement hardware will be available and compatible as well.