I've had people ask for our DS's number and I won't give it to them and sometimes the person gets mad, at that point I remind them that SS #'s are not a form of ID and that minors aren't required to show ID. I offer to give them mine or DH's but they usually end up saying that they don't really need a number
I realize you didn't ask this but IMO dr's and hospitals are asking for #'s of minors more and more b/c they want all of their health related info linked to them by SS# so when unviersal health care is made mandatory for all citizens the govt will have everything it needs to catagorize people according to health risks

A dr's office recently asked my DS if he wears his seatbelt all the time, what physical activities he's in, and etc, questions that had nothing to do with the reason DS was there. The questions didn't last long until I interrupted and told the nurse to direct all of the questions to me, the questioning stopped at that point, go figure

. Please no flaming, that's jmo, no one has to agree