I charge for STATS because
1. it is common in my area, for both home and centres
2. Most parents are getting paid for STATS as well even though they aren't working
3. I don't take paid sick or vacation days and feel that this is a small perk to me being the boss and making my own rules.
If I found that parents were complaining about having to pay my STAT fee ($10 less a regular day) I would instead charge a higher fee throughout the year and be closed without pay on STATS. I have thankfully never had a parent question this (at least not that I remember! lol)