The difference is most definitely there. My total comp as a SWE5 at Facebook in London was closer to what this article calls "Entry Level" in the Bay Area.
Vital word: “was”. Do you know what SWE5’s in London are being offered today? I make offers and I can tell you that it’s a discount to be in London, but it’s not _that_ big of a discount.
This was 2017. I doubt the market has moved that much in 3 years?
Which would be my other point, you need to pick which city in Europe you’re comparing to. Kiev will get you results that match your statement, but London will not. Specifically using the EU, Zurich will not match, but Bucharest might.