Behold the basic principle of supply and demand! Smaller time sellers of birds/pets will go to such markets and buy some of those young looking poached birds to resell at their shop for a markup to hopeful pet owners. Because they keep selling for the poachers, bird dealers and pet shop owners, this sad tale will keep happening because they bring in money for everyone involved. This is where a lot of unweaned baby birds in that part of the world come from too- the pet shop owners source these birds from these kind of conditions. To my understanding, in regions of the world alexandrine are native or sold commonly in nearby countries, if they aren’t banded and from a reputable breeder they are almost guaranteed to be poached illegally from the wild.
Hopefully people in the parts of the world where this is still viewed by many as an acceptable practice start protesting and educating others about how unethical it is to steal young birds from the wild and shove them in cages like that. Then people interested in owning pet birds would demand better practices and sellers of birds would either implement better practices or go out of business.