Reminds of being a young guy and feeling annoyed when girls are being let into clubs for free without waiting in line, and I had to wait in line and pay. Sometimes I could not get in because the club was "full", but the girls would be allowed in.
In the 80's a club near me got into some sort of trouble for that so they switched to skirt night - only a tiny number of men were willing to wear a skirt to get in free.
It used to be that promoters were paid per woman they brought to the club and nothing for men, and they would in turn charge a cover per man.
No idea how these businesses operate now. I'm sure there's still sliding scales of sliminess based on the quality of the club and its management.
If the service is free, you are the product :-)