There's an inbuilt distrust of the federal government built into the constitution itself and there's a constant drumbeat from the Republican side that the federal government is wasteful and out of touch with the needs of the individual states, often for practical purposes of devolving control of funding and policy to the state level where in general they have more control.
And as to why the SSN is the way it is, it's a usage of convenience. Before the SSN there was no unique identifier for every citizen then suddenly to keep track of the new entitlement and assistance programs during the great depression one was created and companies started using it as they wanted because it was the most convenient uuid available. There's a good recent CGP Grey video about the history of SSN and why it's such a silly mess today.
And as to why the SSN is the way it is, it's a usage of convenience. Before the SSN there was no unique identifier for every citizen then suddenly to keep track of the new entitlement and assistance programs during the great depression one was created and companies started using it as they wanted because it was the most convenient uuid available. There's a good recent CGP Grey video about the history of SSN and why it's such a silly mess today.
https://www.youtube.com/watch?v=Erp8IAUouus