Masks are problematic in the UK because for the first three months the government told everyone there was no science that they were effective. They then switched to fining people who don't wear them where it's legally required.
I suspect it was because they'd messed up on pandemic stockpiling and supply and didn't want to have to compete with the public to source them in the short term.
Once that was over they changed tack and the mixed messages are causing problems. They claimed both decisions were science led at the time which has the unforeseen for them (but entirely predictable for us in this thread) effect of making people doubt the science at the worst time in history to introduce those doubts.
The claim, 'we are following the science.' Was and is, to justify and reinforce policy. The issue is, is they are 'finding the science opinion' that fits the policies, they wish to impose. As you said: The 'policy' was to hold back PPE for the medical workers, so the WHO advice to wear a mask, was suppressed and the science they found and followed. Fitted into the example of: If you have enough distance between people, then a mask, will make little difference to the transmission rates. This 'is' sound scientific advice, because it is true; just not fit for purpose, in the real world.
Again. The policy is, to keep the kids off of the streets and mums and dads back to working normally. So the science states and proves, the virus hits kids less, (one box ticked) with correct social distancing, the spread is reduced, (another box ticked). Hands washing as often as possible, also helps reduce spread, (three boxes ticked) What more solid scientific facts, do you need to force schools to stay open? They can ignore the science, that states kids are mostly asymptomatic. Or that kids just don't get it, when told how important social distancing is; as these things do not fit the policy they wish to impose.
Just like the law, someone can twist the science, to fit almost whatever they wish too. They even have the standby excuse: 'Well this is a new virus and we don't know enough about it and so we may have to change the science lead advice.' Rubbish. The pandemic play book has been written and tested and it works. Test, trace, confine and contain: From day one, hard and fast, without compromise.
Another prime example: Before Xmass the UK was basically locked down by the world. All of the places basically said. Get a negative test and you can come into our country and so lorry drivers etc., had to be tested to transport goods and now that 'is' the standard procedure. However: Due to opposition from the U.K. travel industry, airports etc and the still lack of testing kits in the U.K. People coming into the U.K. have not been compulsory tested, until this week and the way it is being done; to prevent blockages, is a joke. Get a test, leave the airport, get a text later stating you are positive and must self isolate.