Incentives for behavior modification is always a fascinating area.
In this case, the daycare was incentivized to track people being late more closely since they had a financial interest in doing so. I suspect the outcome was somewhere in the middle of more accurate record keeping and introducing the ability for the parents to pay off their guilt.
It presents a choice where there wasn't one before. Without the fine, most people wouldn't even consider choosing to be late. In general, people tend to choose from the options in front of them, so paying attention to the options you provide is very important.
But also, you'd feel guilty for making people wait for you, but with this you'd just think "Oh I won't make it in time, but no worries, it's just 5 more dollars [or whatever the rate is]."
