“ Society as a whole is more and more splitting up into two great hostile camps, into two great classes directly facing each other — Bourgeoisie and Proletariat.”
https://www.marxists.org/archive/marx/works/1848/communist-manifesto/ch01.htm
If you read what I just sent, Marx refuted Adam Smith’s concept of “previous accumulation” with the reality of primitive accumulation that preceded all capitalist economies.
https://www.encyclopedia.com/social-sciences/applied-and-social-sciences-magazines/primitive-accumulation
Hey! Actually, Marx’s companion in theory, Friedrich Engels, was the son of a wealthy English textile manufacturer and had direct experience in workshops, and used his privileged position to interview workers and author his work The Condition of the Working Class in England.
Also, if you read Marx’s Das Kapital, it is full of detailed accounts of different production processes, especially with regard to machines and other tools of production (very crucial to his theory of value), as well as long chapters like The Working Day which reviews some reports and accounts documented by factory inspectors and child labor commissions; this is where you read about statistics revealing how 12 or 16+ hour working days were shortening worker’s lifespans, people collapsing from overwork, injuries, very uneducated minor children doing hazardous work for capitalists, how capitalists defied laws regulating child labor with a relay system that circulated them through the factories, how workers were packed into factories and deprived of air, weekly starvation deaths etc.
Even if you think you don’t agree with Karl Marx and his ideas, Das Kapital is a very influential book worth checking out!