I think that's just standard across the US. But the unions are a people problem not a company problem necessarily. People can still form unions even with massive investments to squash them.. Europe has proven that. But the story told to all US workers SEEMS to be, you have to suffer and grind to make money.
I might be wrong but that's the impression I get when talking with US people about unions and workers rights.
If Silicon Valley had unions, employee stock options would end. And along with it, most of the incentive structure that drives innovation in the valley.
Unions primarily benefit the weakest workers, and in places like SV, usually the top workers already are getting fat plates and others are pushing hard to get there.
Think of it like a football club holding a vote to flatten player pay. The benchwarmers will be falling over themselves to unionize, and the top players will be looking where to move too.
This is why union efforts fail, which many find perplexing. The most valuable players get better deals negotiating without a union.