You do expect that all doors will behave like doors. If you try the handle (assuming nothing stops you from physically reaching the door), you'll either open them or fail because they are locked. If they are locked, they'll usually make a noise (either because you pull and the lock won't let it open, or because the handle will not continue down).
The main complain about the whole door thing is that you find games that have what looks like a door and isn't: you click your action key and it does nothing because what you are seeing looks only like a door. It'd be fine if it behaved like a locked door, but not even that. It simply ISN'T a door. It's just a painting of a door.
Also, all doors open. Whether you need to unlock/unblock them first or not is another thing. But doors open.