Old-Age and Survivors Insurance (OASI) provides benefits to retired workers and their families and to survivors of deceased workers;
Disability Insurance (DI) provides benefits to eligible workers who have qualifying disabilities, and their eligible family members; and
Supplemental Security Income (SSI) provides income for aged, blind, or disabled individuals with limited income and resources.
Food Stamps is handled through your very own local "agency" which isn't part of Social Security Administration. Food Stamps are run by United States Department of Agriculture.
I'd guess most of the folks in that particular waiting room are there for the purpose of proving who they are to people who assemble and review documentation pertaining to applications for SSI, DI and OASI.
The day I applied for Social Security the waiting room at our SSA was occupied mostly by white people. Interestingly enough they only had 12 parking spaces ~ so most folks had to be dropped off.
You can apply for SS on line. No waiting lines.
Last winter, I had occasion to go to the local SSA office...took an number and waited my turn. My sense was that I was at the UN building in NYC. I was the *only* Western person in the room. A majority of the people, of all age ranges were Spanish, Far Eastern [Oriental] and Russian. It was unnerving.
The SSA employees were very patient, polite and kind, much nicer than the DMV workers, I’ve encountered.