There is an anti-discrimination law that has never been passed, but is fully in force - for better or worse. You cannot discriminate among women based on physical attractiveness.
It started with airline stewardesses. To say you were dating a stewardess in the 60's and into the '70's, it was a big fucking deal. Then the airlines were told that they couldn't really put these stews out to pasture when they were no longer young and attractive, and they couldn't continue demanding that new applicants be "hot," and it became a sick joke to even talking about dating a stewardess. They would just as likely be - let's say - NOT attractive as otherwise. And of course they started hiring largely gay stewards, which threw that whole paradigm into a ditch.
Around the same time, HS cheerleading went through a similar transition. The cheerleaders had always been the cutest, most popular girls in the school, but the parents of chubby girls who had paid for dance, ballet, and gymnastics classes for ten years began screaming in School Board meetings that their little darlings should not be excluded just because they were homely and relatively fat. Now that paradigm is dead.
Hooters was a part of that same mind-set, created when it was still OK to only hire cute and/or sexy girls, and the girls themselves considered it an honor to be hired into jobs that were typified by the Playboy Bunny. There were "key clubs" around the country who hired little dumplings for men to flirt with and cop the occasional feel, and everyone was cool with it but the girls and women who were excluded simply because they didn't fit the profile.
Hooters servers have been a sick joke for at least 20 years, with most of them being the opposite of cute and/or sexy. It's a miracle that Hooters has survived this long.
Perhaps the more important question is, if the clientele were happy with the original concept and would still be today, and if there would be no problem hiring cute and sexy girls to work there today, why can Hooters not exist today in its original form?
Political correctness run amok.
Remember, there is still no LAW prohibiting discrimination on the basis of physical attractiveness.