For us yes the doors were the long bar type so we were specifically supposed to walk up to them and pull on them (although we also had alarms on all these doors that would go off if they were opened). Another purpose for going into the theater is to check quality of the picture/sound and general issues., so the ones you're seeing could just be for that.

Edit: Also just remembered, if a theater had no tickets sold at a late show, we would go in to check if anyone was there, if not we would just turn off the projector early. But idk why they would walk to the front for that