The article quotes the average starting salary at google to be $125,000. After converting that into GBP (for the UK where I live) you get to 77,613.
Europeans quote salaries (usually monthly) after taxes, and Americans use pre-tax numbers. They also pay a higher tax rate (and get more, like real health coverage). So when you hear a European say that he makes 4000 Euros per month, that's an after-tax number and it's actually comparable to about $80,000 pre-tax salary in the US.