So you're in a car accident on the way and wake up in the hospital with a few thousand dollars in fines. Or better yet, pass out at home (in spite of being in good health; blood pressure can do weird things) with no witnesses and come to a few hours later.
If you were in a car accident, chances are that the day care would waive the fee. The fee doesn't exist to be needlessly cruel, it's there to encourage parents to pick up their children before closing.
As far as passing out in your home for a few hours. If that were really an issue for you, then potentially paying $600 might motivate you to actually go see a doctor. Otherwise there could come a day when you pass out and never wake up (and your children never get picked up by you or see you alive again)...
Even if there are no extreme cases like this, the stress of $10*num_of_min fine is not worth it. It seems disproportionate by a huge margin, and may contribute to bad health issues (e.g. blood pressure).
