I TOTALLY understand the the rules, BUT...and this is a big BUT...there is sometimes more to the story.
I had a lovely experience at a daycare we used for a brief period of time. DD and DS had only been there a couple weeks when I received a call that DD was ill - she had pooped more than ~whatever number of times~ within an hour. Hmm..okay. Weird thing was, no issues with BMs at home...?!?! She didn't seem the least bit ill. Well, whatever...we made it work.
The next week, something similar. Then it was a fever. Ever other week - and sometimes more frequently - she was sent home for something. And never ONCE did we see what they were reporting. How could that be?!
Very quickly, I got smart and started counting kids in the infant room when I went to pick up my "sick" child. Hmm...over the allowed number of kids per teacher for that age group. Go figure.
Then I received a call, it was a fever of 101.9. I RACE to daycare (DD was very small and that was scary high to me at the time) and by the time I arrived, I had an appointment for her to be seen. Literally 20 minutes after the call that she was sick, she was in an exam room being seen at the ped's. No fever.
None. Umm...WTH?
So...I truck her back to daycare along with a note from the pediatrician. Guess whose kid didn't get "sick" at that daycare any more? As far as we could tell, it was a total scam. They didn't want to have another teacher in the room, so on days they were overcrowded, they'd switch off which parent had a "sick" kid.
ETA: They actually commented on being over the ratio when I brought DD back that day!!!!
We immediately began looking for another daycare and found one that we ADORE. DD has been there since she was about seven months old, and we love it. If we get a call from them, I know something is honestly wrong.
All of that said, I would never bring a child back (or in) until they'd been fever free for 24 hours, and if they are put on antibiotics for something contagious, they don't go back until they've been on them 24 hours even if they don't have a fever. Who wants to spread that crud around, right?!