Train line, with many stops, we’ll simplify it to make the explanation simple. Actual in game is 7-8 stops in a line.
A -> B -> C -> B -> A
In this scenario when the train reaches A or C it should unload completely. There is no reason anyone who is on the train should want to stay on the train. If they get on at B they should be getting on in the direction appropriate for them and shouldn’t be going to C if they mean to go to A and shouldn’t be going to A if they mean to go to C.
What I noticed when setting trains up for upgrades/replacement. I would put a depot at the end of the line. Wait for a train come in unload to only 1-2 passengers left and send to depot. Minimizing fare loss. Also allowing the passengers to go to their transfer and make more money. If I just hit it right away the passengers would teleport and transfer fares would be lost.
What I noticed was that on some trains, roughly half, the passengers would only count down to 15-25 then suddenly start filling up again. This isn’t a case of passengers getting on before getting off, as it didn’t happen every time, and as I stated above, there is no logical reason for them to be stay on the train at all. There multiple well spaced trains on the tracks so there is no way for it to be faster for them to ride around the loop at the end (especially when there are actually 7-8 stations in this line)
The most obvious explanation is that passengers are getting on on the wrong side contrary to all logic. Another explanation is some kind of bug with passengers, but it isn’t clear what. We can’t track an individual passenger who is already on the train since it’s about to fill up with a bunch of people and there is no way to isolate them reliably.