OP, not RTFT yet but your view is rather simplistic.
I normally work 2 afternoons pw in a primary school. Before half term we had around 35 children in every day, vulnerable & key workers' children. The senior leadership team has completed risk assessments over every part of the wider opening. Some classes are in mobile classrooms with toilets so they can be used. Lots are in interconnected spaces in the 1930s building and they are more difficult to keep separate. Some staff cannot work due to shielding (themselves or members of their household).
The risk assessments had to go to governors (remotely) then to the Local Authority to be signed off. Lots of things that the children normally enjoy won't be able to be used as social distancing cannot be maintained.
Because we have to make provision for those children already in school, there is not space for all of Reception, Year 1 and Year 6. Luckily, our parents have been really understanding. They know we are doing our best and at the end of the day, trying to keep them and their children safe.
To those going on about WW2, yes my dad was a schoolboy then and keeps telling us about how he took his gas mask blah blah. Whilst life was dangerous then with the threat of bombs, the children could all be huddled together in the air raid shelters. We can't do that now.
I am honestly sick of the teacher/school-bashing that goes on here. If it's so simple and obvious, you sort it out. Set my lessons for me remotely, chase up the missing work, mark it and give individual feedback. My internet connection has already gone down 3 times today despite being promised fibre broadband by the government which has, needless to say, failed to materialise. I'm doing my very best to keep as many people happy and comments like these make me want to just give up.