On a Location, often a door is operated by a door closing device. Normally for filming, this poses little problems. They become a problem when a Set build is part of the equation.
When a door closer is installed on a Set wall, the results can be dramatic. The pressure created by the mechanism is enough to rip up a typical set flat, giving the Standby Carpenter way too much to do, if you're lucky enough to have one. Set walls not only need to be reinforced internally to support them, the walls need to be secure, as the tension will disperse throughout the whole wall. This can be a real issue on a sensitive location install.
Its often difficult to cheat a door closer. Doors that are operated by door closers behave in a distinct way. A hotel door, for example, would read as odd if it wasn't mechanically operated. Likewise School doors.
For example, a shot of children bursting into a School hall would look odd because the doors would fly open, whereas in reality, the doors want to close, and they would only open enough for the flow.