Flexible Professor's Wage

What makes economics professors (well, Jim Hamilton, to be precise) different from their non-economics colleagues (to be exact, the other UC's professors)?

The former is more willing to adjust their price and take salary cut (and be explicit about the term, instead of using an obscure word of furlough), when the economy goes bust, and demand for economics teaching and research down.

Of course when thing is the other way around, no difference between the two. Both would love to have a raise.