I don't have kids of my own, but I do have a niece and nephew. I also remember my upbringing as well.
I must be honest I do find the idea of grandparents not helping out to be a bit alien. I had my grandparents on my mum's side who lived round the corner from school, so I would walk back there after school and get picked up by my mum after work, and then my grandparents on my dad's side where from Runcorn so I would see them when I could.
And they were both heavily involved and glad for it honestly. With both my mum and dad working, up until I was a bit older to look after myself (or at the very least not be too much of a burden on my older sister) I would go there after school, or during the school holiday, because my parents were working and my grandparents were happy to help.
Now with my niece and nephew, my mum and dad are happy to take care of them whenever; they stay over at least once a week, my mum helps out with the child care, they are very involved. Same goes with the other branches of my mum's family - grandparents were always very involved. And generally everyone in the family is involved, we are quite closely knit.
I do know the in-laws for my sister are not as involved, and frankly seem a bit out out by kids. My sister likened it to "seen and not heard" in that Nan would want a picture with the kids to look all gran like, but then won't play with them or interact much at all. No one is forcing the kids on them, but they are a bit miffed that she doesn't want to be a part of their lives, or interact with them much when they are with her. Grandad is in Australia so I guess that's something of a let off.