I hope that gun range does something about their lax gun rental policy. If the other stolen gun ends up being used in a crime, and someone gets hurt or killed, they’ll be sued out of business.
My local range only allows one to be rented at a time. I also can’t see them letting someone just leave a gun unattended at the firing station (from their perspective) so that someone can go out to their car.
Sloppiness all around.
When you leave the range, staff takes control of the rental weapons until you reenter the range seems the sensible way to handle that.
I used to shoot at that range all of the time back in the 80's. They were a pretty laid back bunch of folks. The only thing they got their shorts in a bunch about back then was people firing full magnum rounds in the range. They'd go out the back wall some times.