Fire code is usually not a problem with systems of this sort, which are already in use in many parts of the US. Typically, the back of the store has a conventional armored door with peephole, which can also be used as a hasty exit if needed. If you have a key, of course.
What does happen is often that armed robbers are so stupid, that once inside, they rob, then go back into the airlock to escape, point their gun at a clerk (with laminate between them), and demand to be let out. Not only won’t the bullets go through the laminate, but the clerk just ducks down behind the counter and calmly calls the police for a pick up.
You can't have more than one motion to exit. Insert key (1), turn key (2), turn knob (3).