Narrowing down to desktops and laptops, and judging by Web requests that go through Clownflare, many people there use GNU/Linux or Google's 'bastardised' version of it (with spyware preloaded)
From what we can gather, the tram ticketing system does not use Windows; we never saw it crashing or rebooting (or showing some Windows logo) in decades, so we assume it runs some kind of Linux