Real or not, this does sound like it could have happened. No one really does much research in things like this. You expect parking fees, someone asks for parking fees so you pay them. Everyone in the zoo thinks the other guy counts the money..
It's a neat story anyway. I like it. Might give lots of people ideas they didn't have before.
Reminds me of a couple of years ago, folks were collecting money for some charity or other, so when I saw a teen aged girl standing at a stop light the third day in a row, I began to wonder when I saw other teen girls sitting in a near by parked car guzzling sodas. I cruised by, stopped to read the sign she was holding, and yanked out a camera and loudly told her how nice it would be to put her picture in the paper...she whirled around and ran in front of other cars to get to her friends and they left rapidly. It was right before school started, she must have needed new clothes. I don't trust anyone much anymore.