It is purely a hard-left power grab, just like at Kickstarter when they unionised for the pure, noble purpose of forcing their employer to allow fundraisers that were threatening violence against conservatives (and thus had been taken down as a ToS violation).
As a former Googler myself (not for quite some years), I see this as the inevitable end result of always kowtowing and giving in to ever more radical left extremism. It started with nice but trivial sounding language about how there should be more women in tech, and it ends with hiring endless full time activists like Timnit Gebru.
If Google is ever to regain its former glory, it needs a serious purge. There won't be one: instead I suspect it will become a cautionary tale spoken about quietly throughout the world, for many decades to come. The lesson drawn will be: don't hire SJWs or else you might end up like Google did, with managers being deposed by a unionised mob demanding endless and ever-spiralling purity warns.
Should your waiter, your dentist, your auto mechanic, your daycare worker, your landscaper, etc. have a say in your decisions? They're your employees, albeit temporarily, so why not?
The shareholders are the owners of the company, not employees. The right to set the direction of the company belongs to its owners. The profits belong its owners, just as your paycheck and what to do with it belongs solely to you.
(As an aside on shareholders and compensation, considering how many FAANG people have huge chunks of their compensation in stock, people are well aware unionizing at a FAANG is basically people attempting to pick their own pockets since increasing employee compensation (themselves) is taken from shareholders (themselves).)
Unless employees make up 100% of the shareholders that is trivially not true.
They already have a very well defined leveling system. The promotion and hiring system - people hate - but it is as un-nepotistic as possible and (I think) fairer than pretty much anywhere else.
The compensation is already higher than basically everywhere - as you mentioned - ESPECIALLY considering expectations for your work.
And, sure, I think no one in America gets enough time off. We could maybe squeeze out 5 weeks of PTO for all employees.
Originally, I thought, is that worth unionizing for? I didn't think so.
HOWEVER, Googlers have since convinced me that this is more about employees having a voice in corporate decisions than compensation. For example (and I don't really agree with this) - most Googlers are VERY much against Google working with the DoD. They want to be able to use unions to block that. Others want to use unions to force Google to be more transparent about what it's doing with data and so on. Others want a better way for employees to speak up when we do things that seem illegal (breaking GDPR rules) or extremely unethical (hypnotizing babies on YouTube for ad-money). Currently, as with most companies, Google is a company that really cares only about maximizing shareholder value. Most Googlers were hired when the Google slogan was "Do no evil" and they really took that to heart. And for a long time, that WAS true. Now, a lot of them (and current employees) feel differently. And they think unions can bring "Do no evil" back to our main corporate guideline.
I'm not sure I'm convinced this is worth it or possible, but (to me) it's DEFINITELY more convincing than the compensation / working conditions argument.
If we unionizing and employees get a stronger corporate voice AND 5+ weeks PTO, I'll be very happy. But it seems like a pipe dream to me.