Andrew C
You know what's funny?
First. This has not much to do with preemptive closures. Second, the problems you state exist are due to the crappy way these we are handling schools currently.The districts closed this year right now that I know of, are lacking staff or have over 1/4 of the kids out. Schools always close with excessive absences. Now I only know my area, but not one school is closed that doesn't have a valid excuse. It literally is that bad now. Even my district I am seeing more cases per day than I'd see all week or even all month previously. The below poverty level districts here are out of subs and out of ability to send kids and have them watched properly. So if the school is closed they have food for the kids and chromebooks and hot spots. When you cannot open, you adapt. Many schools have thanks to federal aid.
I think if there are unions pushing for closures find out why and make sure we are not risking losing more teachers for next year when getting a solution. My kid's bus driver quit due to risk so we're now on bus driver #4 this year. That happens when you push too far too. Most schools are far beyond closing for no cause now. If there are exceptions then deal with it, but as a whole what you are claiming just isn't happening.
really, all schools should be operating in a relatively normal fashion. Teachers and kids should come to school when they feel well and stay home when they feel ill. And once they feel well again, come back. No tracking of cases. No mandated testing or isolation periods or any of that stuff. No well kids or teachers at home waiting for test results. Drop that all. You will see attendance go up for both kids and teachers. Asymptomatic kids and teachers sitting at home does more harm than good. And closing schools just because you are worried about spread is a horrible position to have.