My office is located on the first floor of a building. We also take up some space in the basement. Above us is a parking garage.
Since people other than us can get into the building through the parking garage and via elevators, we have to use keycards to get in any door except the main door during business hours. This includes the basement.
A couple weeks ago I found the stairs. You don't need a keycard to get into the stairwell in the way that you do not need one to get onto an elevator. Are you still with me?
To get to the basement you can take the elevators and then are dropped off in a hall and have to use your keycard to get into our part of the basement. However, if you take the stairs to the basement, you can't get out of the stairwell and into the basement hall without using your keycard...and then you are in the hall with the elevators and have to get out your keycard again to get into our part of the basement.
I guess they don't want random able-bodied people to get into the basement at all but don't care about the handicapped or those with bad knees or those who are just lazy...