The obvious

Lady M. can only think this is some sort of security measure(not having a lone woman in the exit booth) , but obviously there's something else here for someone to benefit monetarily. It's Mexico!!

That was my initial thought, too, until Devney and others mentioned that this is how it's done at all the "modern" airports, which reminded me that THIS airport is operated by a very "special" Spanish consortium that has no love for Zihuatanejo and could care less that for 40 years we've had a booth there. I'm sure they see it as simply another of their penny-pinching methods to increase their profits, particularly considering that for the past couple of years our airport has had such little business that I'm sure even the parking lot attendant's salary wasn't covered by the daily income since almost nobody was using the lot. So even though now that business is back, they've ditched the booth and aren't about to change their minds. And apparently it STILL doesn't occur to anyone at the airport to put a simple friggin' SIGN up. But you can bet your Maltese bippy that everyone got their Christmas bonus!

Madness!