Are labor unions like uaw and seiu communist?

I would suggest you do the research yourself.

Look up the history of unions in the U.S.

Research who founded them.

Trace their background.

Research the current Unions and who they vote for.

Research SEIU, AFL-CIO, and others.

Research their leaders

Trace their careers and affiliations.

Also, research Karl Marx

Research Communism in Germany and in Russia

Research Progressivism in the U.S.

ALL THE CONNECTIONS ARE THERE. YOU JUST NEED TO FIND THEM