[jpalomaki]

It's a similar as described in Freakonomics book.

Daycare was annoyed with parents picking up their kids late. They introduced a fee for this. As a result, late pick ups increased.

Something that was not considered to be socially acceptable, became more acceptable when you put a price tag for it.

[verbify]

Clearly the fine wasn't high enough.

[bell-cot]

Was the actual goal to stop the behavior? Or to cover their staffing & overhead costs for the extra time?

[guappa]

What they should have done is call the cops and report abandoned children :)

[pferde]

No, what they should have done is to increase the fine progressively for repeat offenders.