Science

Plastics are a byproduct of fossil fuel production, and it was and is inevitable (under capitalism) that the overproduction of plastic would lead to the manufactured demand for massive amounts of plastic goods. There was a major marketing push in the 1950s to sell consumers on the disposability of plastic, to create further demand by erasing their Great Depression/wartime-era habits of saving and reusing. There are many examples of successful campaigns to put the masses on cheap garbage, like corn syrup, that people would not have been drawn to spontaneously. These things work.

Fossil fuel companies are major centers of political power, with deep military-industrial ties, easily acquiring politicians and regulators, and encircling any stubborn holdouts. Something major would have to displace them to free up the kind of political oxygen needed for any serious effort to end plastic's invasive presence in our lives.

A decolonial not-for-profit military answerable to a socialist state could dislodge them, and I don't think anything less could.