TIL the screens on a bus show a static html stored in a one drive directory. The gps location gets sent to an API which then updates the HTML file in the bucket. The screen just reloads itself every 10 seconds.
Usually there is some reason behind the decision. This may be used by less tech literate people so having the familiarity of windows would be useful, or maybe the machines that are mass purchased are from a company with windows pre installed and it isn't worth swapping. Maybe someone in the company is helping a friend offload licenses at cost to the company. Sure Linux would work perfectly fine, but it's not like it's going to improve the profit of a company or stability to such a high degree that it's worth it.
Computers should never run day to day operations using an account with full administrative privileges and for Windows computers, the default full admin account is called Administrator. It's not so bad on a personal device but for businesses and public facing computers it's like asking someone to hack your computer. All anyone would need to do to compromise that system is plug in a keyboard and they could install remote control software or anything else they wanted. I hope that explanation helps!