Unions aren't just about protecting jobs. They play a critical role in job conditions as well. The most obvious example is the unpaid overtime we all are forced to provide (on call, weekend work to meet crazy exec deadlines etc) simply because we are classified as 'exempt' employees.
Also, classic factory unions are not the only kind possible. The SAG is a good example of a union representing (often) highly paid workers and primarily negotiates working conditions and a (low) floor on pay.
The fundamental reality is that except for a vanishingly small number, tech workers have zero leverage against employers individually.
The tech folks mistook a longish boom as evidence of their genius and skill. As long as demand outpaced supply of tech workers, the going was good. Once the tides turned, we're finding out the reality of where we stand with respect to the oligarchs.
This isn't new however. We've always been subject to these cycles. Expecting a union to mitigate cycles is a fantasy. All it can do is protect the mediocre that are displaced by the AI. We saw the same reaction when companies began to employ more contractors and offshore more work. The mistake is to believe that we are somehow experiencing something new. We're not. If you've ever worked in an environment where the management supported "top-ranking", it's similar, except it occurred once or twice a year. No one is guaranteed a job. What I see here are concerns from people whose primary job seems to be coding, likely most on the web based applications. These were always commodity jobs as Amazon told me a decade ago. The value that tech people bring are understanding the business, the problem, and proposing solutions. As of now, AI cannot do that effectively. Instead of hoping for unions to mitigate the displacement or shorten the work week, a better strategy is to figure out how to be irreplaceable. If you're slinging code for 40+ hours a week, you have ALWAYS been disposable.