Most companies do, if they're made in impoverished populations. And the ones that are made here, in the US, just rape the land, and if it's a job a teenager could do, they call it a summer job, or work program.
Most large chocolate makers go way beyond just the standard corporate exploitation used by most corporations, which granted, is bad itself.
It's worse considering the area it occurs in, West Africa, that it's almost entirely a luxury product people don't need, that it's often children put into de facto slavery, and all the corporations are profitable enough they could just pay to do it ethically if they wanted.
I don't know about Hershey anymore, but Nestle is bad and just about all of them extensively exploited people now or at one point.