I think most if not all of us "professionals" aren't gonna talk about what we are paid.
Certainly supply & demand help set the rates and the supply of fully qualified and type rated Captains is much smaller than commercial multi-engine co-pilots. Tighter supply = higher price.
Unions monopoly of a skilled labor force theory is just that.... a theory. In reality ALPA has been unable to keep pilot salaries in line with inflation since the dawn of deregulation.
1. An airline pilot is nothing more than a glorified bus driver. True. I know what I am and pulling to the side of the road when things break is just a wee bit tougher than for a bus driver.
2. I earn my salary once a trip.
I earn my annual salary once a month.
I earn everybody's annual salary once a year.
Just some things to think about.