They look at your resume, see that your background is "better" than the job you're applying for, and assume you'll be unhappy in the job (even if you know you're willing to take any job at all). In reality, a good part of the time, even if you're willing to take any job and be happy to do your best at it; they're usually right about your being miserable (at least secretly) if they hire you. :) Other factors, they know you've been making more than they the way to pay, and they don't think you'll be happy with less money. They know you've got years of experience and think you won't want to report to someone who may have less experience than you (that type of thing). Another one: They know you're x years old and have x years experience in x job. They know the people you'd be working with are younger, have fewer years experience, etc.; and they don't think you'll fit in well with them (which you probably won't).