One of the articles linked by this one goes into detail how automation has impacted union workers at ports.

An estimated 572 full-time jobs at the Ports of Los Angeles and Long Beach were lost in 2020 and 2021 to automation. Meanwhile, profits for the global shipping industry soared during the pandemic to over $190 billion in 2021, as the rate to ship a 40-foot container increased from less than $2,000 in 2019 to as much as $20,000 in 2021

The union is demanding that “no automated or semi-automated” systems be introduced. This will be an interesting strike to watch out for.