Here is the US there are some people with concerns that someone could grab some merchandise and run out the door with it.
They put magnetic locks on the doors to sound an alarm and delay opening the doors so that the security people have time to respond (usually 15-30 seconds. When there's a fire alarm, the delay is bypassed and the doors release automatically; specifically to avoid the scenario of trapping someone inside a burning building because you were originally trying to stop a shoplifter.
