Conveniently omitting the 20k strong walkout. That's organizing.
I hadn't heard that it was for all cases, kudos to Google. But of course that is just one example among many.
Unions are structured in a way determined by the workers who are voting, there is no inevitable path for a union to take. A teacher union is very different from an actor's union, for instance, even if they are covered by the same basic laws.
https://fcw.com/articles/2020/05/20/google-cloud-diu-william...
https://www.nbcnews.com/tech/tech-news/thousands-contracts-h...
https://www.foxbusiness.com/technology/cia-awards-cloud-comp... (Not DoD, but the US IC)
This has allowed the management to make promises to address concerns and fail to follow through on them. Or have HR take over employee-organized community groups discussing grievances and slowly let them die.