Maybe in your country they also don't have a deposit on bottles/cans, making it pointless to go through trash cans?

Not OP but many people eligible for social benefits don't seek it, for all kinds of reasons (not knowing about it, pride, ideology, peer pressure, ...)

Keep in mind that not every old person who searches garbage bins is actually poor. Some of them just have dementia. I personally know such people in my home town.

That's why I said "mostly"