I hate to break it to anyone but most locked doors can be opened "in seconds" by a variety of means. For the most part the locked state is a signal of prohibition, rather than a meaningful enforcement thereof.
However you can only flipper doors that are held closed by the latch bolt. If the lock deadbolt is engaged, you cannot flipper it, because the deadbolt will not budge when manipulated by a card or piece of plastic.
Technically a lock without an engaged deadbolt is not really "locked" but "closed". That being said, an unbelievable amount of people believe their doors are locked when in fact they are closed.
They're about making it inconvenient enough / loud enough to gain unauthorized access that someone is going to notice and complain to the manager.
This is a bit harder when said window is only reachable from the outside, and is 78m above ground level (and all the walls are brick, so they're stronger than the wooden door).