Here governments take decision for the short term because they have to please the common (& uneducated) men for the next election. Hence the agenda of environment doesn't get much attention. That's why have poor plastic management.
Educating people about these issues will take decades (& it will be too late). Only way forward could be if some constant external pressure is put on their governments using agreements/accords (like Paris Agreement) and some system is setup which will monitor issues like plastic management and carbon-emission. If countries are not following some standard they should be penalized.
Countries like US, Canada, Germany can take initiatives in doing so. Its not only about their carbon-emission & plastic-management, its about the whole planet.
Developing countries should be pressurized(!!) for reducing their population as well. In India, from past 2 decades, no government had an agenda to control population (which is the root of all the problems here). With some external pressure this could also be done I guess.
And most importantly, large & impactful countries like US and China shouldn't waste their time on petty issues like trade-war & focus on big issue here!