Imho the biggest shock to the labor market has been the baby boomers dropping out of the labor market, whether for full or part time work.
Fear of Covid started the trend last year.
The red hot stock market gave many seniors with retirement savings there less need to work.
Many have interesting hobbies which became small work at home businesses.
That is a big chunk of the low wage labor market, since traditionally many seniors would semi-retire and keep a low wage job on the side (partially for the extra money and partially for the social contact).
I see old farts working the checkout lines at grocery stores. And I think you're right about the social contact and probably a little spare change for gifts to the grandchildren. I recognize one who was a superindendent in my home town many years ago. He surely has a generous pension and doesn't need the money. Just likes chatting up the ladies. Plus the geezers actually show up for work every day and on time.