So what if you work in this factory and the owner doesn't pay you.
Why would you voluntarily work for a person who doesn't pay you?
I don't assume everyone in society is honest. I do assume most people in society are smart enough to manage their own affairs.
But, to answer your question, if you aren't paid for your work, you can sue for the debt. Every jurisdiction in America has a small-claims court where filing fees are minimal and there is no need to hire a litigator to represent you.
I'm a law clerk who was married to a carpenter. No you can't just sue. You have to be able to fill out the papers. Very few working class people could do that correctly or even know how to do it. You have to be able to present your case to the judge in a cohesive way, and your corporate employer will have a lawyer there claiming you shouldn't be paid. You have to take time off your current job to try to recover wages from your last job. If you're only owed $500 it's probably not worth it.
You seem to think you get paid right there in the court. You might have to file your order with the sheriff to seize property, or garnishee wages. I have never know a working class person who successful recovered lost wages in this way.
The courts are a poor remedy for employment abuses. Labour laws were designed to eliminate such abuses by setting standards of behaviour for employers.
Most people are smart enough to take care of themselves and and their bills, but to have the smarts to advocate for themselves, and get the best deal for themselves in a competitive situation, few and far between. Most people lack the skills or confidence to negotiate their own car deals. They're now hiring people to do the negotiating for them. I was a consumer loans manager in a big bank. Our working class customers, were honest hard working people, but lacking the education or the skills to negotiate.
So what if you work in this factory and the owner doesn't pay you. What recourse do you have? All of this libertarian bullshit assumes that everyone is honest and will do the right thing, and that everyone will tradely fairly and honestly with everyone else.
At will employment gives all power to the owner and none to the worker. You said it yourself, you don't like it leave. Your boss wants you to work unsafe conditions, leave. Walmart comes in and sets up shop, hires away all of your workers with higher wages and benefits, undercuts your prices and drives you and all of the rest of the mom and pop retailers, out of business. Then they cut wages and raise prices. There's nowhere else left to work. That's how the Walton's got rich. Their size and capital allowed them to do that.
Expecting people with wealth and power to treat lesser beings fairly or ethically, is ridiculous. Labour laws exist because the Robber Barons locked their workers into unsafe factories and hundreds died in fires, or got chewed up the machinery and their bosses did nothing.
To bring you up to date, this is October 11, 2020, not 1920.
Considering that wages, as a percentage of costs, are currently at the same level as they were during the Guilded Age. Over the past 40 years, businesses have absorbed increases in the cost of materials, supplies, rent, real estate, furniture, fixtures, transportation, utilities, technology, professional services (lawyers, accountants), and virtually everything they need to operate EXCEPT wages. Corporations are booking record profits and paying out huge executive bonuses and dividends, and corporations were awash in cash, even as W crashed the economy throwing millions out of work.
Executive Salaries went through the roof. Up 1000% in some sectors. The GDP went up, up, up, and American workers were the most productive in the world. Front line worker haven't benefitted from any of this. Wages flatlined, expecially after Reagan destroyed the union movement by telling workers the unions were screwing them, and everyone would get a big raise when the unions were gone. The unions are gone, and workers are still waiting for that raise.
When pressed to raise wages in light of the rise in GDP and executive wages, their response was the increased GDP was due to automation, not more productive workers, and so the workers didn't deserve the raises. They also claimed they American companies couldn't effectively compete on the world markets if they raised wages - all while booking the biggest profits, and highest dividends in history.
So not, it's not 1920, but for front line workers it may as well be. They're getting poorer and poorer, and the rich are getting richer and richer, off their labours. The more things change, the more they stay the same.