I worked in childcare about 20 years ago, and we charged $1 per minute late.
We had to keep two staff there, and they would split the fine.
Many times we got stiffed.
Edit: for reference, our fee was about $14/day to keep the kid, so it was a pretty stiff penalty.
> Many times we got stiffed.
I understand that you could not keep the child till you were paid (kidnapping and ransom shouldn't be a business plan!), but you could refuse them future service until they paid.
Well, If the staff got stiffed on the fee "many times", and the parents were allowed to bring their kid back.. the place didn't charge $1 per minute late. They just bluffed and got called on it.
(apologies for the immediate edit, changed my wording)