Should we still have separate tags for specific national versions of these like
SSN for the USA or
BSN for the Netherlands or
NI-Num for the UK?
Such consilidation is dangerous if based on false premises. There are many different IDs, that have many different purposes: passports, personal IDs, national IDs (something like SSN in USA), tax ids etc.
If the question is about the documents allowing to identify a person, maybe identification would be the best. However, please allow specific tags, if used for specific purposes. For example, ssn for questions about getting SSN in USA.
I propose that we consolidate all national identification numbers into one tag. Questions should anyway be tagged with the country, and national-id-number along with a country-specific tag should be enough to find country-specific questions.
The only exception I can think of is if a country has multiple systems for national id numbers. But that should apply only to a small minority of questions, if any.
Note that there is no National Identity number in the UK.
There is a National Insurance Number, but on the National Insurance Number card it specifically says "This is not proof of identity". I think it's worth respecting that, and not merging it with the "national-id-number" tag. They are definitely not the same thing. The NI Number is closer to a personal tax number than an ID number.
As per Łukasz 웃 L ツ, there will be different purposes and different numbers. If we merge things, we should do so with a clear understanding of what the numbers mean, rather than merging and regretting it later.