Common sense is,
Buy a coffee, common sense would say that that coffee would be hot and therefore caution should be taken when drinking it until it has cooled down slightly.
The general public these days need a warning sign on their coffee advising them it is hot.
How have we got down to this dumbed down state?
Is the public getting generally more stupid?
Another example
A saw has sharp blades and when used they cut, it's obvious why you are buying a saw, also it would be obvious that that saw has the potential to cause you bodily harm, but again the saw must have warnings plastered over it to advise that this may cause damage because there are buffoons out their that lack the common sense to think for themselves.
With this covid caper it's down to the individual, if they feel that they need to go on holiday for their own sanity or whatever then it would be expected that they carry out all precautions and are fully aware of the risks and the paperwork required.
This isn't a matter of law, it's a matter of whether people feel they need to go on holiday.
The government can't implement a complete ban on travel as it would decimate an industry that has already been severely affected by covid, there is also a while wider industry reliant on the travel industry aswell.
But at the same time the government can't say everyone is free to travel and Dona's they like because the likes of the guardian will lambast them even further and blame them for even more deaths etc etc.
So it's really no wonder the government advise is not black and white and it is being left to the individuals to make their own decisions.