But if only 2% of plastics worldwide is traded (source: same article I linked in my previous comment), and most of that is traded within the same region, how much waste could possibly end up getting shipped to less developed countries and burned? You'd still be better off trying to reduce domestic garbage production/burning in those countries.
I don't know of good figures on how much worse it is to burn plastic rather than wash and reuse it.
what do you expect they'll burn for power if we stop paying them to take stuff to burn?
This is ideal, at least in arc and high temperature, scrubbed plants (because plastic recycling takes more energy than burning it cleanly.)
But you likely intended burned less as fuel and more as a disposal method.