I live near the beach in Japan. I admit that I don't go and pick up plastic off the beach. I definitely should because it's not really an onerous task. I'll try to schedule it occasionally (I mean, I'm near enough that I can actually
walk to the beach, anytime I want).
However, on the beach near me, there isn't much garbage. And pretty much any day I go, there is a group of students picking up garbage on the beach. When I used to work at the school, each home room would have beach days where they go and pick up garbage. And each club has beach days where they go and pick up garbage.
I live on Suruga bay, so it's not right on the Pacific and I'm sure that cuts down a lot of the garbage. But just with the local high school sending 20 people down there practically every day, it seems to keep it under control.
It's one of those cultural things. There is garbage everywhere because we don't have a culture to clean it up. We feel like we shouldn't have to. We feel like it should be someone else's job. Maybe that's true and maybe it's not, but a consistent effort by a small group of people can make a big difference.