The problem is this is effectively a reputation score; only you have very limited rights to see it* (once a year, per agency; and only if you ask... Oh and BTW, I pulled /all/ of mine just before it came out that the breach happened; :( )

Also a problem; they use simple knowledge of a single magic number as authentication ('identification').

The three current companies in the US could have gotten together and worked around the lack of a national ID and created a private SIN cryptographic... but that would cut in to their profits. Though I hear other countries that have done this also have issues with 'business individuals' being contacted and scam attempts rampantly abusing their data...