Sweatshops as a necessary evil has been a hallmark of the ideology of capital ever since 19th century Britain. The 1844 book by Engels,
The Condition of the Working Class in England, basically a report on the sweatshops of the time, was a huge influence on Marx. From the preface:
> Having, at the same time, ample opportunity to watch the middle-classes, your opponents, I soon came to the conclusion that you are right, perfectly right in expecting no support whatever from them. Their interest is diametrically opposed to yours, though they always will try to maintain the contrary and to make you believe in their most hearty sympathy with your fates. Their doings give them the lie. I hope to have collected more than sufficient evidence of the fact, that -- be their words what they please -- the middle-classes intend in reality nothing else but to enrich themselves by your labour while they can sell its produce, and to abandon you to starvation as soon as they cannot make a profit by this indirect trade in human flesh. What have they done to prove their professed goodwill towards you? Have they ever paid any serious attention to your grievances? Have they done more than paying the expenses of half-a-dozen commissions of inquiry, whose voluminous reports are damned to everlasting slumber among heaps of waste paper on the shelves of the Home Office? Have they even done as much as to compile from those rotting blue-books a single readable book from which everybody might easily get some information on the condition of the great majority of "free-born Britons"? Not they indeed, those are things they do not like to speak of -- they have left it to a foreigner to inform the civilised world of the degrading situation you have to live in.