People in stations, on vehicles and in public buildings are usually in a hurry and often somewhere unfamiliar. They need to know where to go and what has changed, at a glance. A sign that is wrong is worse than no sign.
The settings are demanding. A screen at a stop or in a car park faces sun, rain, cold and the occasional knock. A screen on a bus or in a taxi runs from the vehicle's supply and is shaken all day.
The harder part is keeping information current: who publishes changes, how quickly they appear and what a screen shows when its connection drops. That is a content management question to settle before anything is installed.