Doesn't matter. An employee in Google London is paid lesser than the employee in Google SF. So while you can cry about injustices and rationality, salaries will likely be paid based on cost of living and even geography (based on London example).
Strange reply. I'm not talking about injustices. I'm saying a company would be pretty dumb to pay someone more just because of where they chose to live. Profit maximization and all that.
You should ask yourself: do I want to hire people who decide relocating to Silicon Valley would be good for their career, or those who can't or won't?
Google made $65 billion in 2014[0], and had ~20k engineers[1], which puts the number per engineer at $3.5 million. [0] https://www.macrotrends.net/stocks/charts/GOOG/alphabet/reve... [1]https://www.quora.com/How-many-software-engineers-does-Googl...
That's only the case if skilled engineers are fungible entities with a smooth supply/demand curve. That is absolutely not the case.