School zones on my daily commute

So I drive past a school every morning on my way to work, and I've yet to see a single child anywhere in the schoolyard. Yet the school zone demands that I not exceed 20mph - it's for the children, don't you know. Yet I do see a number children waiting to be picked up by the bus on my morning commute, and never a school speed zone to protect them from the dangers of the cars that speed past them.

Perhaps I shouldn't say this out loud (lest some authoritarian hear and implement this) but if we're going to reduce auto speeds and generate traffic bottlenecks near schools (which seem to be peppered throughout the city) "for the children" the why is it that we don't just limit traffic speeds for the entire country (excluding perhaps highways where there wouldn't be any kids waiting for a ride to school) to 20 mph from 6-8 am and 2-4 pm?

Of course a nationwide 20 mph during commute hours is a STUPID idea, and that's part of my point in suggesting it. The other part being the idiocy of placing bottleneck school zones throughout every city in the United States. Now there are probably a lot of schools where it is appropriate to require speed zones, places where there may not be fences or high walls surrounding them. Places where some of the students walk along the sidewalk to get there. I think those are totally appropriate places to require speed reductions. And, to be fair, I suspect that most schools fall into that category. But not all of them, probably not even a sizable minority of them.

The more general idea I'm on here is that I think it better to deal with situations on their own rather than with blanket, one-size-fits-all policies. Put appropriate school zones as necessary where they can be defended, because they should need to be defended - they impose a time cost on the rest of society, and given that time is one measure of life, that is a cost to the mortality of us all.