I'm certainly no expert, but it's my impression that workers for large corporations generally get screwed when unions are weak. Based on data from the past several decades.
Unions were very weak in the late 19th century, because the only tools at their disposal were extra-judicial violence, which was met with state retaliation. During that period, when contracting rights were at their strongest, workers saw wages grow at the fastest rate in US history.
Unions in the private sector became much weaker over the last 40 years, but that was not due to the labor laws that empower unions being eased. It was due to the type of industries that unions are prone to form in (e.g. labor-intensive, high volume manufacturing) contracting in the US.
The laws that empower unions make the US inhospitable to key industries.
What's going to happen to the US electric car manufacturing industry if Tesla's workers unionize?
What's going to happen to Amazon's business units if they see massive unionization?
The consequences for a US-based operation when their work force unionizes is a major disincentive for investing in production in the US, and a major impediment to existing US-centred companies from expanding.
You're basically just arguing that corporations will operate where there's the best mix of worker ability and low wages. That's understandable, but short-sighted. Because poor people aren't good customers.
It's a prisoners' dilemma thing. Businesses that can move production to low-wage countries are leeching off businesses that can't move. Also, it rather destroys the concept of a nation, where workers and businesses depend on each other.
When wages were rapidly growing in the late 19th century, the US offered the highest wages in the world.
It's possible to have both high wages and competitive production facilities. That happens when the skill-set of the workforce and the infrastructure and supply-chain of the nation improve enough to compensate for the higher wages.
Forcing companies to pay wages that are above the level that they would be at if left to market forces results in parties in the US less effectively utilizing labor and capital to raise productivity. Less productivity growth ultimately means less wage growth.
The wage boost that comes from a law mandating companies pay higher wages is a one time event, that results from an increase in labor's share of total income, and comes at the expense of lower recurring boosts to wages, because the disruption to the economy caused by such a law reduces the rate of economic growth.
So laws that force companies to pay higher wages mean, in the long run, people being poorer than they would otherwise be.
Unions in the private sector became much weaker over the last 40 years, but that was not due to the labor laws that empower unions being eased. It was due to the type of industries that unions are prone to form in (e.g. labor-intensive, high volume manufacturing) contracting in the US.
The laws that empower unions make the US inhospitable to key industries.
What's going to happen to the US electric car manufacturing industry if Tesla's workers unionize?
What's going to happen to Amazon's business units if they see massive unionization?
The consequences for a US-based operation when their work force unionizes is a major disincentive for investing in production in the US, and a major impediment to existing US-centred companies from expanding.