I never said otherwise. I was saying that a serf in the middle ages had it more or less equally good as modern migrant workers.
Do migrant workers live in drafty one room houses with leaky roofs no windows and dirt floors? Serfs did. Do migrant workers diet consist of onion, potatoes and bread? Serfs did. Migrant workers work 40-50 hours a weeks while serfs worked 60-80 hours a week.
The kind that lack a legal right to work, work for illegally low wages
Any wages a person with no legal right to work makes are illegal wages. They choose to enter the country illegally and work illegally why should anyone be shocked if they are paid illegally.
Now you need a bunch of machines for most of it and a bunch of Mexicans for a small remainder. If it took as many people to design/build/maintain the machines as it did to do the work manually, there would not have been any gains in productivity, which is contradicted by reality. So we can agree that we need fewer people to do the same work, and yet somehow we still need everyone working full time? I call bullshit.
There are many assumptions you make that lead to this wrong conclusion, or maybe it's just your way of convincing yourself it's ok to be lazy.
-There are fewer people farming then there was 600 years ago, this means fewer people are doing the farming for a larger population
-You seem to think society has not gotten any more complex, there is not just a carpenter, blacksmith, and farmer any more. All the people that would be farming are doing something else, thousands of job fields that have to serve the whole population.
-Now if people use technology to do just enough to get by they are setting themselves up for failure, when their technology breaks they will have to work harder to fix it or pay to have it fixed and thus will now have to work harder to maintain their same lifestyle.
Gains in efficiency are disproportionately pocketed by the wealthy
Gains in efficiency are pocked by the by the people paying for the technology, if migrant workers are not paying for the technology then they won't see as much of the benefit. Why should the person risking their capital forfeit the benefits?