Over 9 crore Aadhaar enrolments rejected by UIDAI (Zee News)
Out of 823.3 million enrollments, 97.3 million (Approx. 12%) have been rejected for reasons of either quality or duplication.
This may seem to be high to some, or low to others. In the big picture, there is (or should be!) a cost-benefit analysis at the beginning of the project that gets at the expense of the process vs. the infallibility of the process. On the first pass, it might make sense to get the highest proportion of good enrollments with the most convenient process, then to engage in a more expensive enrollment process applied only to more difficult enrollments.
It's also important to note that the 97.3 million rejected enrollments contain both duplicate applications, which must be rejected and other applications where clerical error, fraud, or un-enrollable biometrics are the reason for rejection.
Another interesting statistic in the article is that only about 618,000 UID numbers have been issued under the "Biometric Exception Clause" which allows for creating UID numbers for people whose biometrics cannot be enrolled. That comes out to around 0.07%.
What that means is that (depending on the number of people waiting for a biometric exception) using a data set approaching a billion individuals, at least 99.3% of the population of India is biometrically enrollable within the existing UID enrollment process.
Note: The article uses the Indian numbering units crore and lakh.
1 crore = 10,000,000
1 lakh = 100,000
See also: UID applications without biometrics highly likely fraudulent
