Actually, the German model makes a lot of sense. It's pure maths, based on a rolling infection rate threshold of 50 people per 100,000 population in the last 7 days. So, it makes short-term decision making very simple and predictable. Wiki will happily tell you what the population of your region of interest is. You calculate the cases per 100,000 and draw the conclusions on whether they're anywhere close to the threshold. If you've been unlucky enough to find yourself somewhere where the numbers exceed the threshold, you're given the choice of either undergoing a compulsory test upon arrival to Germany or, if you feel that this is too much of an intrusion into your privacy, you may instead stay in quarantine for 14 days. Bloody good way of mitigating risk and keeping the economy running at the same time.
Some keen defenders of the UK model will now say that the test might not always detect infection. Fair enough, it can happen. But, in the UK version of things, people in "self-isolation" are nonetheless allowed to go shopping for essentials and participate in some other, albeit very limited activities. What's the chance that someone infected and untested will infect a whole bunch of people in his local Tesco? And what's the chance that they will also go elsewhere, using the excuse that they were going for essentials if stopped by the police? I think that it's more or less the same as that of someone with a false negative test doing the same. So, in terms of risk mitigation, "self-isolation" is no better than testing. It either has to be proper quarantine with zero contacts with the outer world - or it serves no practical purpose.
Now, the conspiracy theories that the government is deliberately destroying aviation in order to not have to deal with stuff like the LHR expansion - I cannot comment on that, it might be true or it might not be. But, for sure, there are alternatives which could keep many companies in business and many people employed. Why they are not being implemented is not for me to say.