This does cause problems, but maybe if schools acknowledged that they were childcare they would be better equipped to deal with some of those problems? Or even the structure of schools might change to better accommodate this requirement.

Now whether or not schools should be primarily childcare is an entirely separate debate.

Exactly.

If schools explicitly acknowledged their dual purpose, then they could more cleanly separate the two functions. I think doing so would even improve the educational component.

I've volunteered in high school classrooms quite a lot. The amount of wasted time is astounding. Hours upon hours of boring nonsense that somehow actively detracts from learning. Students are so bored from sitting around all day. Also, they instinctively learn that 80% of every lecture period is filler nonsense but are quite bad at guessing which 20% they should be paying attention to.

Even in subjects that shouldn't be cut (e.g., Geometry) the lecture periods could be safely halved and probably improve educational outcomes.

Schools are great facilities for child care, BTW. Computers, gyms, fields, sports equipment, books, ...

Why not just admit that about half of the classroom time alotted to most subjects exists for fill-up-butt-in-seat-time purposes only and then openly embrace the fact that the school is an educational institution whose physical plant is also useful for leisure/childcare? Heck, university campuses already do this...

They are sending them because they are legally required to do so. There is nothing optional about it for most people. Parents have their jobs planned around their kids being at school -- again, because it is a legal requirement that the kids be there. Suddenly withdrawing that -- going on indefinitely now -- is causing all sorts of strain, especially in households where the parents can't work from home.