Through labor organization. It wasn’t out of the goodness of the hearts of benevolent Capitalists, but through struggles of Workers. The point of this picture isn’t that Capitalism used to be worse, and fixed itself, but that Capitalists will absolutely take advantage of children and subject them to sacrificing their bodies for clean chimneys if it makes a profit.

The takeaway from this is that Capitalists cannot be seen as individual humans with values, but as cogs in the Capitalist machine that will exploit everything and everyone for profit. An individual Capitalist may not be willing to go that far, but inevitably as long as there is profit to be made, someone will fill that gap.

That’s why economic systems need to be looked at at aggregates and not as individual transactions. You miss the forest for the trees.