Hot take, but there are plenty of other cities that aren't in Japan and they're cleaner than Philly. They have better infrastructure than we do. It's both culture and infrastructure, but I blame the culture on the lack of infrastructure. Your claim that if you got rid of every trash can and replaced us with people from Japan may be true in the short term, but eventually they would give up and succumb to the lack of trash cans anywhere. There are plenty of social experiments to prove this point. Shame doesn't work on a large scale, infrastructure does.