My wife isn't eligeable for a SSN number until our immigration process is complete. She has to use a personal TIN (tax payer identification number). No other agency or private company can require the use of an SSN unless it is for business with the social security administration. You legally can't use it for a driver liscence or for anything else.
Actually a priave or public business can legally use it as an ID number provided you give them permission to use it and so long as they inform you that you are not required to give them your SSN and can request a different ID be used. This is the legal loophole for the business. Once you surrender your right to privacy for your SSN, the person you give it to can use it anyway they want. Check the law and you will see that I am correct. I went through this for many months with lawyers at the hospital I worked at to make sure that SSN usage for employee IDs was in compliance with SSA law.