That's basically what the article says: elevator doors (in the US) have a minimum open time, as specified by the ADA, and try to close as soon as this minimum t

That's basically what the article says: elevator doors (in the US) have a minimum open time, as specified by the ADA, and try to close as soon as this minimum time is reached. The close button can't override the minimum, so generally it seems like the button does nothing. Meanwhile, some elevators (hospitals are the example given) do hold the door open longer than the minimum, and the close button works in those places, per their testing.