The MTA in NYC can't seem to make this work correctly for trains

At our (penultimate aboveground) stop you can look down the track and see if there are any trains waiting - even if there aren't, the live board still likes to claim there's one 'coming in a minute'

My only guess is it works off of what should be happening, and not what actually is going on

It works fine for the trains and busses, you either don't live in NYC or don't know what you're talking about? The MTA app and displays are almost dead on accurate for arrival times for the busses and trains. Sometimes there's a minute or so of a difference from reality but that's more than small enough to be useful.

I was talking specifically about the display boards, not the app