Make up days are a good idea if the center has any capacity to give you an extra day, but then what about parents who already utilise 5 days a week.

How do private schools do it? You pay per term right? Does the term fee change depending on number of days actually at school that term? Or kinders that pay by the term do their rates change? (I don't know the answers to those questions) but can think of quite a few term based activities where sessions don't run on public holidays and your term fee is the same.

I suppose the way I see it user will pay whatever, either by paying on the day or in the general daily rate - and there are so many other issues with childcare accessibility and affordability that paying on public holidays doesn't rate that highly on the list.
(Although centers being open on public holidays and better hours, Saturdays etc for non 9-5 workers I think is important)

Also a 'hotel' based system where the cost per day depends on the demand for the day (which is one of the way hotels for example work) would be a very bad idea in my opinion.