Earlier quoted context omitted.
The propaganda unfortunately also comes from folks direct experience with unions. In the US, most unions are public sector. So folks see that Police unions may protect bad apples via union. Teachers unions may care more about teachers including bad ones then teaching kids. We had a famously terrible teacher at my school - unfirable - as kids we thought it was hilarious. As a parent now - not so cool. Non unionized sc…
The problem is when anecdotes about isolated abuses are used to reject unions outright rather than looking at whether unions as a whole would benefit society. You could argue from personal experience that you went to a bad school therefore all schools are bad, or you had a bad experience with therefore all people of that sort are bad. It's just not very convincing.
There are plenty of examples of unions being really bad in the US, the burden of proof is now on the other side of the court.