Ugh, this is disgusting and so patronising. Edit: Also, why are "union avoidance consultants" a thing? The US needs to fix its culture around unions. That's absolutely wild.
Lots of analysis could be done around the macro-socio-economics of the why, but in general I believe it’s because of the availability of remote, work starved populations, historically concentrated capital, and ease (from a cultural and legal perspective) of moving businesses and doing intracountry trade, have meant there was generally always a place industry could move, get what they want (including cheap labor), and sell to the same customer base or maket. Labor loses a lot of power when the company can just up and go somewhere else. This has historically been harder in Europe due to historically hard border controls and strong national identities - it will be interesting to see how this shakes out in the EU!
This is obviously not absolute (or Labor would not have gotten the power it has now, which is still non trivial in the US), but it is much more the case than Europe, where Labor has been able to dictate terms for awhile, and movements related to this problem were major contributors to the world wars.
One could also make arguments around shortage of labor in Europe due to deaths from the many world wars (which had only a minor impact on the US), or the world wars weakening the established sources of Capital or control in Europe more than the US, or shifts in population phenotypes due to mass migration to the Americas and susceptibility to certain types of working conditions or living styles (are children of folks who immigrate for work more like to move for jobs and take harsh living conditions as part of the deal?).
Overall, it’s hard to not notice that no one seems to actually be enforcing labor laws designed to protect workers, or that Labor isn’t organizing effectively and using it’s muscle. That may be changing, but especially on the low end it seems kinda unlikely right now.