We have locked trains on server in Zelenogorsk, and when players tried to open it, it make no "locked sound".

Players were then thinking its just server desync issue and not that those trains are locked.

It is of course possible to open them with lockpick, but sound same as for doors should be there.

Lock train

Try to open it

No sound of locked doors is played, so it looks like server lags / high ping if nothing is happening