I live in this tall building.
When I come home, to get in, I wave my access card at the sensor for the gate at the bottom, open the gate, walk to the lift—um, that is, the elevator—and push the ‘up’ button. Typically an elevator door opens right away.
It used to be that sometimes the access card gate would be propped open.
One day, I was so tired when I came home that I went through the gate without really noticing that it was propped open and proceeded to wave my access card at the elevator button.