Edit: summary at https://en.m.wikipedia.org/wiki/Electronic_waste_in_China
There's far more stuff coming from China to the west than vice-versa. A ship can't travel empty, but needs to be ballasted with an appropriate weight of cargo. If there isn't enough booked cargo on the return leg to China, they'll make up the weight with scrap metal or rubble.
Sure, send them back to China, I don't care, it just seems silly that we would all just mail our broken junk back one piece at a time to AMazon who then puts it in a container and sends it to China.
Better to take it to alocal recycling facility for them to send it en masse. Have Amazon give you a voucher to handle the recycling fee.
Still, Amazon just gifted me an item when I tried to return it since I ordered it by mistake (and I was honest on the form). I wouldn't be surprised if they tried to avoid recycling returns too.
It seems like a better idea would be to just have Amazon give you a voucher for the recycling fees in your local community.