Except it wouldn't really cover the edge cases. Less than a buck for a kilo isn't worth hauling back that amount of trash to a teenager so it SHOULDN'T have solved the problem at all and either you'd still have all the adults attempting to scalp the litter or you'd have even younger kids flooding the dungeon for what they think is easy candy money and dying even more often.
This isn't some secretly clever satire of government incompetence, if it was then the problem still wouldn't be solved in universe, they'd just fudge numbers to claim it was with everyone else being able to see there's still just as much if not more trash, scalpers, and child corpses everywhere. This was just the author creating a stupid bit of world building to explain why the shy girl was poor and thus even more (sim)pathetic. Which I will again state, could have been done in an even funnier way but having her be very bad with money.