Graduating with a compsci degree doesn’t cut it at companies like Google. Having 4 years of school in the IT area isn’t enough. Just because you can code doesn’t mean you have the width and depth of background for some of these companies.
It takes a particular kind of mindset to be effective at these companies, one that comes from a life-long immersion in technology. You have to know about interconnected ideas schools can’t really teach well. You need to know about the old tech too, legacy stuff, why it’s not used and what current technology is based on it. You need to know WHY a function calls what it does, who originally wrote that api and when was that?