When DC were young, I met quite a few grandparents who were doing full time work hours care. They complained a lot as they felt tied down & this should have been their free time, but felt pressured because they were retired and 'free'.
I vividly remember two grandmothers high fiving each other when their youngest GDC were off to school as they had a few hours a day free. My aunt let slip frustration about the constant holiday care for her 3 DGC - my cousin & her DH are earning millions but still expect free child care.
I think helping out like a community is a lot different to the pressure to committing to many hours of regular care that is expected now. From playgroup to school & DC activities, there are some kids who I've never seen the parents, just grandparents.
My own DP's do one day a week in school holidays. Which is more than I expected as they weren't around for us at all.