The key word here is safe return and "the medical community" is not advocating for all schools just to open and have kids there 5 days a week in all circumstances. Here's a quote from that link and this is where the problem comes in.
"Local school leaders, public health experts, educators and parents must be at the center of decisions about how and when to reopen schools, taking into account the spread of COVID-19 in their communities and the capacities of school districts to adapt safety protocols to make in-person learning safe and feasible. For instance, schools in areas with high levels of COVID-19 community spread should not be compelled to reopen against the judgment of local experts. A one-size-fits-all approach is not appropriate for return to school decisions.
Reopening schools in a way that maximizes safety, learning, and the well-being of children, teachers, and staff will clearly require substantial new investments in our schools and campuses."
I'm not saying schools shouldn't re-open or that there aren't substantial benefits to kids in having the buildings open. Clearly there are. What I'm saying is that the guidance that exists does not work in so many circumstances that it is virtually useless. There has been no substantial investment in the campuses. There is no way to distance people safely in the structures that many districts have. There are 930 students in the building I work in. My class sizes range from 30-38. The kids sit on top of one another. There is no place to spread them out. There are no unused classrooms in our building there is no money to procure trailers to add additional classrooms and definitely no money to add staff to teach in those classrooms. So we then start talking about staggering schedules. OK, well if a kid is in school twice a week and home the other three, or whatever break out you want, you haven't solved the core reason why so many people want the buildings open, so the parents can go back to work. So what you will have still is a situation where parents either need to be home for kids who are too young to watch themselves, leave the kids home alone, or try to find some sort of day care option that A. has space, B. they can afford, and C. will accept a kid for a select number of days per week.
Here's another example of how the guidance doesn't work. The most recent thing I've heard is to have kids in self-contained pods with one teacher. Well, that works for elementary school just fine. That doesn't work in high school. The teacher who teaches 11th grade English isn't qualified to teach calculus. They aren't certified to do so, they don't have the expertise to do so, and it's not something you can quickly pick up in 3 weeks to be able to do. So either the kids or the teachers need to move. Again working on this pod idea. It is virtually impossible to create a pod of kids at the high school level who are all in the same level of classes across the board. So again, you are either moving the kids around so they can get what they need or you are moving the teachers around. There isn't a way to do that sort of thing at that level. My school is a middle school so it's a bit of all of these issues. The 6th graders are too young to manage themselves at home, everyone moves to different classes and has different levels, you have many teachers who aren't cross trained to teach everything (I am certified to teach every subject and Spec Ed. I'm the only one in my building like that). So how do you do this in a way that achieves people's goals and yet is still safeish.
There are simple problems that I still haven't heard an answer to such as transportation. How do you socially distance on a bus? In order to follow guidelines kids would have to be no more than one to a seat. That cuts your capacity in at least half and younger kids often sit 3 to a seat. There isn't a pool of empty buses (or people to drive them) just sitting around. Staggering schedules might address some of that but then you get into the other issues I mentioned as well as a host more. I work with our transportation company pretty closely coordinating sports buses and I can tell you that they don't have enough drivers in a regular year and a lot of the drivers they have are older people. That is going to be a disaster.
Substitute teachers are similar. Lots are retired teachers. You can't compel them to take assignments, they are able to pick and choose where, when, and if they want to work. I'm expecting MANY of them not to be working this year. So when you have a teacher get sick there isn't going to be a replacement. Again, we have trouble getting subs in a regular year. If we have more than 5 people out in a day normally the additional spots don't get filled. On a Monday or a Friday in the winter it's more like 3 and we can have 10-15 people out sometimes in a regular year. When that happens, and the spots don't get picked up, administrators teach class and/or we consolidate classes into the gym or the auditorium and do what we need to do to get through the day. Well, if you are distancing you can't consolidate classes like that so what do you do? We only have 3 administrators.