Everyone Does It
Regardless of who you are, you step into the empty elevator and don’t think about a camera being hidden. Therefore, you’re likely to do things that other people shouldn’t see. That’s what Tony did on his last day at the police department.
At the end of his day, Tony stepped into the elevator. He had already said goodbye to his friends and co-workers and was quite emotional by that time. Therefore, he waited for the elevator to empty and went inside like always.