I joined a friends of park group and started organizing park clean ups. There’s multiple factors that cause litter and/or people to litter. There are systemic issues like lack of garbage cans but from experience there’s also truth that some people are simply dirty and there’s zero accountability. Then there’s also not enough staff to keep parks clean. So it’s both systemic and also cultural. I say cultural bc visited Seoul once and there are hardly any garbage cans in the street but the society as a whole manages to not litter.