This is common where I am. I get 10 paid personal days (for sick, vacation or anything else), plus stat days and public holidays. Client also pay for the space when child sick or on vacation.
Remember - this isn't babysitting where you pay based on your use. This is a child care which has a set number of spaces. And your fees reserve your child's space.
Considering after business expenses (food, heat, water, laundry, crafts, toys, insurance), we typically get about $2 an hour per client, I don't think having stats and a handful days off a year is a big ask on a 60 hour week.
That said, if someone wanted to pay me like a babysitter, based on just use and have the typically rate that a 12 year old charges of $7.50-$10 a hours, I'd consider that deal and let them have sick/holiday and stats unpaid providing their was a max number of days they could have without fees too. :-) More than happy to take babysitting rate for babysitting terms.