I wonder if Google has trouble with college hires for this reason- people near the end of college are often interviewing with multiple companies at once and timing is critical. Many people I graduated with would have taken a job offer from Google over the one they accepted, but were unwilling to turn down offers from Apple, Microsoft, ect in order to wait for Google to make a decision. Only a couple of people continued the job-hunt process long enough to get a hire/no hire decision from Google.