In all the interviews I've been a part of (1.5 years, maybe ~50 candidates), I've never seen a candidate decline because of salary requirements. We would decide if they were a good hire, and HR would make it happen.
So that's another datapoint confirming empirically patio11's idea that candidates are underasking. If they would ask for their fair value, 50% of companies would decline their candidature because of the price.