When I was involved in the organised far left many years ago, we spent a lot of time trying to get motions passed about this or that cause in union branches. We thought that if we succeeded, as we sometimes did, it was evidence that the working masses were slowly coming over to our point of view.
What it actually meant was that the union machinery as a whole was increasingly disassociated from the working masses. None of the activists were really representative of the members, neither us nor the “right wing bureaucratic misleadership” that we thought we were fighting. The people left taking part in the life of the union were either highly motivated ideological people like us, or ambitious people trying to get a cushy job in the TUC or Labour Party.
The low level of engagement with the organisations of civil society is not a problem unique to trade unions, we see it in the historically low election turnouts and in the political parties as well, and it's corrosive to society.