@Stuart ********
Not sure what you mean by "each to their own"
1) that happened. That's not an interpretation. The officer asked for an updated bank book and needed to see it the next day for stamps to be moved to the new passport.
2) It doesn't prove that during that whole period everything was done correctly. But it would be easily possible to catch SOME cases. Just 1 print below the threshold is all what is needed. The same as a quick look in a car or luggage : IF they find something, then it is proof. If they don't find anything, than it just proves they didn't find anything - nothing else.
It's an extremely low effort way to check.
But the logic doesn't even matter. All that matters is that now at least 1 or more officials have began to check it. Anyone who then has a bank book which doesn't meet the requirements will be in trouble.