Probably because neither Romney and his crew, nor the older white people on Social Security, think of Social Security as “welfare” nor as “dependency on government.”
Nor should they, since (theoretically at least) Social Security funds paid out were originally paid in, though we know this isn’t the case for the younger people on “disability” who draw from the program.
The Social Security administration runs SSA, but they don't pay for it out of the Social Security revenue stream.