These statisticians never factor in the black market. In my opinion, to say that 90% have been vaccinated on account of doses administered makes about as much sense as to say that the vast majority of people stopping drinking during prohibition in the USA. They didn't stop drinking. They just stopped openly drinking.

In the same way, I bet there are populations who pay for vaccinated status without being vaccinated. I bet there are numerous doctors and hospital staff who are awake to the vaccine, talk with each other, and falsify their vaccination status. I bet there are people who pay others to get vaccinated in their name.

The question is, how many? It's certain that at least some of those 90% aren't actually vaccinated, though.