Bill, I too have great respect for Thomas Sowell, but I agree completely with your post:
Paying politicians more to get better service is not the same as paying professionals in the private sector more to get better performance. Politicians have ideological agendas; what they consider good performance depends on their political and economic ideologies. They are not in the business of providing consumers with better goods and services; they are in office to enact the kind of policies that they consider to be fair, just and equitable.
What needs to change is the system itself, and in order for that to happen, the political thinking of the average American has to change.
I would point out that we have at least two major motives that apply to politicians that we can address: Ideology is one, but the other is grabbing some of other peoples money for themselves (and a given politican can and often does have both ideological goals AND greed).
You pointed out that to fix the problem of the wrong ideology requires that the political thinking of the average American has to improve.
But the problem of monetary corruption could be addressed with a constitutional amendment creating an FBI-like agency whose sole purview was the constant monitoring of all nationally elected officials and their appointees, and seeking indictments of those found engaging in corruption. The agency would be run by a board of rotating members, say 13, who are drawn from the 50 state attorney generals. And it would be funded by the the states, not the federal government, on a per-capita basis. The amendment would stipulate that all who accept these national offices grant this agency the right to monitor all of their channels of communication, and financial status. This would be on the understanding that nothing can ever be made public except upon successfully obtaining an indictment for corruption charges (and there would steep felony penalties specified for any leaks of information from anyone in the agency).
A constitutional amendment can be passed by a vote of 38 states and that makes it automatically, and instantly, a part of the constitution without any say from Washington.
This doesn't fix the ideological problem, but it clears out the slimy characters who aren't really there because of ideas, and tell lies - not just to support an ideological position, but to fake even having a particular ideological bent. This clearing out of that kind of crook would make it much easier for the nation to focus on the ideological choices to be made. (And somewhat reduce the congressional/special-interest motivation for giant budgets - i.e., budgets designed to fund not just ideological positions, but aslo illegal money grabs).
As a side note: There is a way to get a minor shift in the ideology of the US Senators. Remove the amendment from the constitution that made the election of the Senators a popular vote instead of a vote in the State congresses. I mention this because, like my proposed amendment for the FBI-like watch-dog, it should be reasonably popular with state legislatures and not unpopular with American voters at large. I think that these two amendments, and maybe a balanced budget amendment, could be passed even though it would require 38 of the states to vote 'yes' on each of them - if they were taken up as a serious, multi-year, well-funded political campaign involving activists, big funders, careful planning and staffing, and grass roots support.
In the long run, nothing will really get the job done but that politically smarter American voter.... but that is a long ways out if we are hoping it will come from the Universities - maybe many generations - assuming the universities ever change from their current direction.