What's the alterative, pay adults a competitive wage? Value for shareholders must be created and we've already sacrificed our children's future environment and economy. Getting upset about sacrificing the actual children to make a buck is a moot point.
Why stop here? The next logical step will be optimizing the process by removing this inefficient phase where animals are involved and going full Soylent mode.
The market is a magical system that both creates value for necessary jobs, and also can't pay people wages for those same valuable jobs, so we need to put children to work.
Children not working is a modern phenomenon in privileged nations. When times get tough and people need to pay bills just to keep food on the table and a roof over their heads, see how fast that changes. And they are about to get tough.
/sarcasm.