clearedforlanding

It's one logic. The problem is it's not the only logical policy you can derive from the all the research that has been done on transmission. And looking at it in terms of cost/benefit I don't see any reason to believe this is the right version of the policy. My simple point would be - the likelihood of a carrier being on a flight is going to vary by location. So vary the policy by starting location. Don't strangle the entire UK aviation sector and all travel with a blunt instrument.

We could also stop pretending the public are stupid and need to be forced to do the right thing. The message should be clear - if you're ill stay at home. As you said - the vast majority of transmission are via symptomatic cases. Right now I wouldn't go out if I had a temperature/cough. The social judgement + some sensible temperature checking at the entry to shops/workplaces would be enough to prevent that, but I also think it's a reasonable responsibility that most willingly accept already. We shouldn't be so cynical of people to make common sense changes to how they behave. Data on cases seems to suggest that the public already did in fact do this before a lockdown was even forced on them. There will not be millions of people arriving at Heathrow magically on June 1 all with zero sense of social responsibility. We should not be preparing a policy to deal with this imaginary scenario.

Assuming the government's goal is to make those cost/benefit decisions on how we go forward (and not just pander to public fear) there are many other things we should be talking about now. Perhaps consider locking down nursing homes and reopening primary schools. Children are vastly not transmission vectors. And nursing homes are the real source of the majority of deaths in Europe.