They’re the primary obstacle to port automation. The US has only 3 fully automated port terminals because the unions throw a tantrum and vow to strike the economy into oblivion whenever they feel threatened by increasing automation.

The east coast union in particular, the ILA, is a real rats nest and it’s a shame they aren’t as impacted by the trade war as the west coast union.

https://en.m.wikipedia.org/wiki/Harold_Daggett