Not directly related to Unions... but look at salaries for SDEs in Europe compared to the US. You can almost 2x-3x a salary for the same job. A large factor is that European companies don't take risks. At least, compared to the US.

https://www.levels.fyi/companies/amazon/salaries/software-en...

https://www.levels.fyi/companies/amazon/salaries/software-en...

In fact, almost any innovative/high-skilled job pays a fraction compared to the US. It is much harder to innovate in Europe.