Tell that to dock workers, who have successfully delayed the automation of ports to the extent we see them automated in e.g. the PRC [0].
Hell, they're even (successfully) pushing back against automated gates! [1]
[0] https://www.cnn.com/2024/10/02/business/dock-workers-strike-...
[1] https://www.npr.org/2024/10/03/nx-s1-5135597/striking-dockwo...
Isn't that just delaying the inevitable? Yangshan Deep-Water Port in Shanghai is one of the most automated ports. Considering there are more people in China than in the US, China still automated their port.
I'm not making a value judgment on the specific case of dock workers, I'm rather saying that unions can and do prevent automation. If Software Devs had unionized earlier, a lot of positions would probably still be around.
The dock owner may not have a lot of alternatives to negotiating with the union. If devs unionize, the work can move.