For example, a provincial auto repair shop might have previously fixed three cars a week but officially reported only one; now it repairs just two cars, but payment for both is fully recorded in the statistics. The government can take pride in such signs of progress, but the wealth of the people under these conditions is not growing — it is declining.
When you're working with data like that, all you can really do is speculate. We'll know for sure only after a few decades I guess
Yeah I think it's very subjective and this one anedcote is just that.
In Germany cash is preferred in most places, and that makes tracking payments difficult. This is not the case in most other european countries. That's an another anecdote for you.