According to your thinking, my department spent four years re-writing every computer program to key on an arbitrary ID number instead of a SSN for nothing... 
That is true: things do change. But let’s look at your own example. What are the heinous impositions brought about by using Social Security numbers for identification?
Even so, there are numerous court/legislative decisions that would have to go the wrong way for even one of your hypotheticals to come about.
Identity theft.
According to your thinking, my department spent four years re-writing every computer program to key on an arbitrary ID number instead of a SSN for nothing...