The number of people who know anything of history at all, even history of their own peoples, their own country, their own family, is "very low". Absent of course the "history" that Hollywood and other popular media pumps out.
I think their point is that most peoole aware of the time period know child labour in factories was prominent, especially thanks to Dickens and other authors, so most would guess or be unsurprised to find these cable factories employed children.
Is this a serious question? Then here’s a serious answer - the difference between employing a 9 year old and a 19 year old for a dangerous job is All the difference in the world.
Did you answer the question? Your answer to "how are they different?" was... "they're different".
Children have been working in dangerous environments since the dawn of humanity. Genuinely interested in why you think the industrial revolution and X years old is where we should draw the line.
Because we reach a certain point where it's possible and reasonable to do so.
The ultimate goal of humanity should be UBI and all humans living a content, peaceful life in which they can pursue the things that interest them.
But because of evolutionary behaviours that result in things like capitalism, we'll never reach that goal. I'll say it now: humans are currently biologically incapable of sustaining a true utopia.