Why is the Alphabet Workers Union filing lawsuits on behalf of people who don't work for Alphabet (e.g. the woman in this article)?
Collective bargaining can be used to make demands about anything really. It doesn’t have to be working conditions for workers. They can even use their power to pressure Google into supporting particular political candidates, etc if they have enough power.
Seems reasonable to me for unions to be involved in lobbying.
There's nothing overtly nefarious about lobbying.
Lobbying is 'telling government about something specific'. Usually in your own interests, but the interests of the people should interest the government.
The problem is the asymmetry of power and access.
https://alphabetworkersunion.org/people/our-union/
We recognize our power as Alphabet workers—full-time employees, temporary employees, vendors, and contractors—comes from our solidarity with one another.[emphasis mine]
Contractors included.