When I was 18..oh so long ago, my first full time job was in a Ballys health club, brand new location (and they were new-ish to the area as well), in the Child Center. I worked there for exactly 2 years to the date!
We were not held to what I now know to be licensing standards of any kind back then (this was 25 years ago). As a few others have said, the establishments argued and at that time did win, that parents were in the same buidling (same floor I think might have been part of it?? not sure, I was young and knew no better).
We had 4 or 5 of us who worked the morning hours, various ages. That was our busiest time, when those aerobics classes went on (think Jane Fonda get ups, with shiny butt floss leotards! LOL). One day we had just over 80 kids on one room (and not a huge one by any means!!). It was more than our normal, but for 3-5 of us, 50 kids for 3 hours was very normal. We did not change diapers or serve food, but would offer a prepared bottle (we did not make them or refrigerate or heat them), no cups or snacks. If a child wet their pants, we did not clean that up either, parents were called over the PA system or pulled off the gym floor.
I am still not sure how we passed fire codes and stuff for that many kids in one space (I remember the fire marshall coming on a busy day with probably 40 kids and 3 or 4 of us working). We DID limit the number of babies and required reservations for them, but still took 2 for every worker, so at least we HAD some standard! LOL
Sounds like things are not overly different at some of these clubs? I do think we offered pretty good care, but geeze, now as a parent, I would never bring my kid to such an over populated place!
Best of luck!