Worker's rights are not an issue when labor is 30% of what they would have to pay in the US for the same skill/talent. US skilled workers don't have it any worse than EU skilled workers, often way better. This isn't flipping burgers at McD's where you have no bargaining power and need unions and labor regulations to protect you.
And you need a lot of skilled people to operate a heavily automated semi fab: PLC programmers, opticians, physicists, material scientists, contractors, HVAC, electricians, plumbers, construction workers, Q/A, etc and irrespectable of workers rights, all those have much lower bargaining power for high wages in the EU than in the US, due to market supply/demand.
Otherwise there would be no investments in the EU and nobody would be making stuff here at all.