That seems like a stretch of the word colonialism. Colonialism usually implies exerting geopolitical control, whereas shipping plastic ‘recycling’ to be sorted has externalized health risks that make it undesirable.
There’s this idea called World Systems theory, that divides the world into core and peripheral countries, with the core countries extracting resources (natural, financial, or labor) and sends pollution back. This is maintained by military and/or economic power. That’s the framework where this would be considered colonial. Personally, I prefer the term neocolonial
The term World Systems theory would use is periphery. Thailand would probably end up in semi-periphery though. Also it is a model best kept in the 90s. Currently it is really having a hard time. Russia for example should be periphery, but acts like a core country.
