We're a Mothers Day Out that follows the public school calendar so we're out 3 days for Thanksgiving, 2 weeks for the Christmas/New Year holiday & other school holidays. However, our parents pay the same amount every month because tuition is averaged out over the school year.
And, even a large facility has expenses. Their teachers may get paid holidays (wish I did!) & there are other expenses that happen whether the school is open or closed.
ETA:
Why does it seem wrong? My job has no paid vacation time. If I take a day off its unpaid. I am not getting paid for the 3 days of Thanksgiving or the week of Spring Break or any time at all during the summer. So, I plan accordingly to make sure I can pay my expenses during the breaks without pay. I would expect any parent who has a child in daycare would plan ahead to make sure they were covered during any holiday breaks.