In my case it was cut out, but then shoved back and taped again.
So at least in some cases, packages get cut, inspected and then carelessly packed back in without regard for the contents.
If it happens 3 times in the same area, then there is indeed more than that going on.

although in the case of London, it might have been paranoia about sharp things. It would not surprise me, given their draconian knife rules, general fear of knives, and the fact that mailing knives is technically illegal. But then I would expect a formal letter to be in the box.