I think that the decision to keep places of education open was purely a decision based on economics.
During the Great first Lockdown nothing opened, the majority of the country stayed at home. yet something went wrong, because the covid virus is still with us. Coming to the end of the Second (pathetic) lockdown we are now in a position of still having the virus but most people are at work to stop the economy tanking, if we were forced into a third, proper lockdown, the kids would be at home meaning the parents couldnt both go to work.
It's a balancing act for the Government. We have to have a functioning country, which means the movement of people, if we lockdown totally again, the virus might (emphasis) be stopped, but at the expense of the economy. So work continues, which means the kids cant be at home.
For what it's worth I have two observations.
Firstly, I work in construction which was allowed to continue duiring the First Great lockdown, our van was the just about the only vehicle on the road, it was astonishing. During this current lockdown it appears to be a normal day on the roads, traffic snarled up as usual.
Secondly, I live in Lincoln a very small city, we have no anti-vaxxer demos, no rioting, no masive street parties yet we are about to hit Tier Three. London is going into Tier Two. Tier Two! It is this sort of blatently wrong, being a bit easier on the capital, that makes me believe that this is now more of a Political Pandemic and not a Medical one.