It should be standard procedure.
If you don't hand in your assignment, you get zero.
Perhaps we could apply only a penalty for assignments that are late.
But there comes a point when a late assignment don't merit a grade.
Of course, given that nobody is held back any more, there's not a big incentive to do assignments on time, at least in elementary school.
We really need to teach kids they need to earn what they get in life.