On positive about a sling, people don't accidentally bang and let doors fly into you. No one wears a sign that says they have TOS. Managing doors is often a real issues, who can open them with out a battle and no one appreciates getting whacked with a moving door.

When in a sling, people take note that you have a problem.
There is more caution to seeing you there to hold a door, or even consideration to open the door when auto doors are not available.
di