Even in 2015, in O'Hare Chicago, there were like 5-6 passengers, including me and family that were late due to a late connection and the flight doors had closed. The bridge was not retracted yet. No one was in the counter either. But we could see the pilots and all of us started yelling and waving at them. They got the door opened and we all got in. That was nice of them. Don't remember if it was United or Delta