Ah, the dance of the doorway! How complex it can be.
If someone ahead of me opens a door and holds it open for me, I'll pass through with a 'Thank You' and hold the door in turn if someone is right behind me. This is known as the 'Do-Si-Do and the Alamande Left'. I may not stop to hold the door if I'm carrying big bags of shopping. If at all possible though, I will put out a foot to keep it open. That can make for an awkward but pretty
little pas de chat.
If I'm the one in front, I will happily hold the door for someone behind me who has an armload of something or who is pushing a stroller. I know security in the building is important but people like that aren't likely to be looking to steal something.
What bothers me is when I'm going into to a shop and the person ahead of me, usually an adolescent
girl, opens the door just enough to slip through and lets the door close in my face. That happened in my own building. I had my keys in one hand and a big bag of groceries in the other. The perp here was a visiting Grandma. As the door closed I heard the older lady say that she did it because, 'That lady doesn't belong here'. Excuse me, at the time, I'd been living in the building for 20 years.
Sometimes, we teach our children a bit too much about 'stranger danger'.