From my European perspective it looks In the US the only unions left are the most hardcore, extremist unions.

All the "finding a common middleground", reasonable unions have been eradicated by anti-union policies. And yes, there are lots of unions like that in the countries that I can speak for (Denmark, Germany).

It is sad to see e.g. police unions being used as an argument against unions in general now.

Unions serve their members, not the public good. Teacher unions do not exist to advance the education of children--they exist to get better hours, pay, and benefits for their members.

That’s a problem with the implementation of US unions, not with unions in general. In other countries things work better.

Police unions aren’t labour unions.

Police break labour strikes, not join them.