I think that almost every grandmother in my area has an old baby carriage to push around. Usually with a brick to weigh it down. I haven't really seen much along the lines of a normal walker here. The little grannies push around their carriages and collect cardboard and newspapers from the recycle piles. Then they stack them neatly. I'm not sure what they do after that. Maybe someone then picks them up to take them to the recycling depot. And they all know each other. Walking down the road, I sometimes see a couple of them walking together... sort of. I think it is almost a competition to see who can get the most cardboard piled up on their buggy. When they see another one down a side street they always call out to them. I often see on little granny pushing a pile of newspapers that is almost a third higher than she is (tied together). She keeps peeking around it to make sure she isn't going to run into anything as she pushes it along. When ever I see her I am worried that the whole stack is going to just topple over. She doesn't seem to worry much about it.
A lot of grannies also sell produce and such on the street corners. I often see them with a little pile of lettuce and a few other things. In some places you can see them selling some sort of root. In others they are selling grains/beans to add to your rice when you cook it. It is always small scale, what ever they are selling. Maybe from a private little garden? I also sometimes see them wandering along the parks digging up certain little plants. I'm not sure what it is they are picking, or why. To add to their salads? To sell on the corner?
The elderly in Korea seem to make up a lot of the work force in terms of the grunt jobs... cleaning. In a lot of the buildings, old women are the ones that do the cleaning. It is usually old men that are cleaning the streets. Maybe it makes them feel useful. Or maybe they are still trying to help support their families, whether it is needed or not. Or maybe no one else wants to do those jobs. Who knows.