It's definitely rosier in most aspects insofar as protection of employee rights is much better at a legislative / public level in Europe, and therefore there's more supports available.

These may however often be your company's HR dept. ticking boxes (HR departments of course by and large existing to protect the company from potential employee complaints first and foremost, rather than to protect employees). In the case of a US-based office where such state-mandated supports are absent, and the employees have put together a body to enable collective bargaining, the supports—while less official and state-supported—may be of more immediate material benefit as they practically address current grievances.

> some EU countries mandate also union members into those

Do you have a reference for this? I'm curious to know which do and which don't (it's certainly not anything that's been brought in at a Directive level).