"Prevailing wages" is one of those statistics that can often be surprising. The bottom line is that some businesses, sample size and definitions of how the jobs are aggregated can drag the average down.
If you classify someone as a "Web Developer" then they will fall in bracket that is ~55% of the "Computer Programmer" bracket (this data is by County so it varies a lot by geography).
AL programmers are paid from 61k to 95k. SF programmers are basically 20+k higher.