For some SDs it is literally against the law for them to do much of anything. Since not all kids have computers, since some kids are special ed and/or are on IEPs they can't legally teach anyone unless they can teach everyone, which they cannot do. That, for example, is what the MA Department of Education has told all MA school districts. They cannot provide instruction and cannot require anyone to learn (or try to learn) anything. All they can do is provide optional "enrichment" if they want to.
I saw an article the other day which I felt made a good case that any school district not going hands-off like that is in violation of federal law and could lose federal funding. And of course states are free to have even more strict egalitarian rules.
(As someone who thinks Harrison Bergeron should be satire, not reality, I think this is all ridiculous, but there we are.)