the reality is that a large proportion of the general population could and is able to be monkey trained up to a standard that can carry out the duties of a pilot.
This is true to a certain extent.
However no airline is willing to spend the amount of money that would bring that to fruition, and second to that, the average punter is not going to put up with the high amount of life disruption that entails with aviation. What is the 'large proportion of the general population' doing on NYE/NYD, Xmas, Easter, Australia Day? They ain't at work.
Additional to this is the average punter may not be able to hold a medical.
So your 'large proportion of the general population' ain't that large anymore.