Capitalism is a powerful economic and social arrangement that produces widepsread prosperity- if labor is not in unlimited supply. A basic concept of price theory, or microeconomics is that the quantity supplied of an item sold in a free market will increase as the supply decreases.
In periods of limited labor supply- the US before the Civil War and from the end of World War II to around 1970- the working man lived well. The lack of an unlimited supply of labor isn’t a problem theoretically for a capitalist or free market. Since things are produced with a combination of labor and capital, capital can be substituted for labor, just as labor can be substituted for capital- not completely, or perfectly, but substantially. If you can hire ten guys at $5 an hour to dig a hole, maybe you don’t need to buy a backhoe and pay one guy $20 an hour. If you can’t hire a bunch of guys for next to nothing, maybe a backhoe is a good investment. Better drive by the Home Depot parking lot first.
As a practical matter- as a empirically observed social phenomena, which libertarians never understand- capitalism insists on having an unlimited supply of labor. Capitalists believe, in a deep, unshakable way that is beyond reason, that they should be able to hire as many workers as they want for any position they want for whatever wages they feel are appropriate to pay.
Libertarians, or libertarian conservatives, again not getting it, point out that the workers obtained under this arrangement will not be friendly to capitalism. In the late 1800’s and early 1900’s it resulted in numerous communists and anarchists entering the US and engaging in domestic terrorism. Currently, they are protesting that the illegal aliens up for amnesty will all vote Democratic.
Capitalism demands cheap labor, but cheap labor demands socialism. Logically this would create a problem, but it doesn’t. Why not?
Because capitalists don’t pay the price- nominally in taxes, or indirectly in the degradation of culture, living conditions and safety- that cheap labor costs. In a modern first world social democracy, higher paid workers, mostly white natives of the nation, pay this cost. If they object they are demonized in the worst possible way.
If there is no expensive labor, no native class capable of demanding its interests, the system will be more crass and directly exploitative. This is what you see in most third world countries, but it’s of no real concern to us. A special situation is South Africa, where white rule was thought to be the problem. In the old days, if black workers got angry and rioted, they would be shot by white (and some black) policemen on the behalf of white capitalists. Of course now, the evil racist regime is gone, and the rioting black workers are shot by black policemen on the behalf of black (and some white) capitalists. Thank God for hope and change!