You're conflating two unrelated issues. The visible plastic garbage scattered around European streets, parks and beaches isn't coming from rivers in Asia, it's

You're conflating two unrelated issues. The visible plastic garbage scattered around European streets, parks and beaches isn't coming from rivers in Asia, it's garbage that's locally thrown away. Reducing the total amount of plastics disposed into the oceans is a worthy but orthogonal goal, by the time it makes it to European shores it's mostly pulverized by ocean activity. The EU also stands to impact world production by its choices. A factory in Asia that's making plastic cups now for the domestic market and for exports might switch entirely to making paper cups if the EU only buys paper cups.