Why do different government entities insist that you provide physical proof of something, instead of just checking their collective data base?

A friend of mine changed her 3 year old daughter’s last name. She got a copy of the new birth certificate, but didn’t think to get a new SS card until she tried to file her taxes.
She called the SS office to find out what she needed. She was told she just needed her daughter’s shot records and they needed to physically see her driver’s license. She took time off to go down there and get all of that done.
Well, a week and a half goes by, then she gets a call that they need the daughter’s amended birth certificate….which she can’t find now. So she’ll have to apply for a copy and wait for it to show up and then ferry it to the SS office. In the meantime her taxes are pending.

Why can’t the SS office just go look it up for themselves? Why can’t the DMV just go look that stuff up themselves?