Child labor is somewhat orthogonal to deplorable conditions. Child actors can easily fit the definition.
There’s also an unfortunate cultural bias where people may view for example Amish children skipping school to take in a harvest as perfectly acceptable when kids in developing economies doing the same things are suddenly not.
Yes, and they often work under deplorable conditions. Psychological/emotional abuse is still abuse (not to mention the forced dieting, the rampant molestation/rape, and other very physical abuses).
But that highlights what makes child labor more worthy of scrutiny. Adult actors face those same conditions, and it's unacceptable that they do, but at least they have the mental maturity to cope with them and the social/legal autonomy to do something about them. Child actors lack any of that; they end up scarred for life over a career they had little choice in pursuing.
Child labor existed long before capitalism. If anything the correlation goes in the other direction with capitalism reducing child labor over time due to it’s dependence on an educated workforce.
While your first statement is true, I'm not sure it follows that there's a reverse correlation.
In fact, I think (having actually changed my response a couple of times while thinking it through) that unless you go back far enough that you're talking about genuine subsistence agriculture, the reasons for child labor are very similar in both cases: The wealthy and powerful take so much of the output of the laborers that without children working as well, there wouldn't be enough money to put food on the table. (Or simply enough food to put on the table.)
We produce enough, as a society, to provide for everyone. Feeding the world in 2023 is a distribution problem. Children are put to work not because it's necessary, but because the few at the top have taken, and continue to gatekeep, so much from the rest of us that too many families don't have a choice.
That's not really different between 2023 and 1023, from where I sit.
There’s also an unfortunate cultural bias where people may view for example Amish children skipping school to take in a harvest as perfectly acceptable when kids in developing economies doing the same things are suddenly not.