RE: Bill Gates makes a case for consumption taxes rather than income taxes
It takes 5years of practical experience to be a bakery manager, that experience includes business education, human resource education, health and safety requirements, financial management, and equipment operation and maintenance education. Bakery managers are paid $36k to $38k annually
It takes 4 years to become a Registered Nurse. Registered Nurses are paid $32k - $43k a year
It takes 8 weeks to become a Real Estate agent. Real Estate agents make $125k - $750k a year
It takes 8 hours to become a notary public. As a notary public I made $45k a year (I was bored out of my mind!)
It takes 4 hours to become a Sanitation Engineer (garbage man), Sanitation Engineers are paid $75k - $125k a year
It takes 20 hours to become a nuclear safety inspector. Nuclear safety inspectors make $125k - $225k per year
It takes about a year and the help of roughly 64,000,000 idiots to become President of the United States. The President has an annual salary of $400k a year
So it's not just school, or "special" skills.
Burger flippers shouldn't make doctor's salaries, but they shouldn't have to pay the same in taxes either. As I said in my original comment, a version of the tax system that ignores income disparity and focuses on CORPORATE INCOME would likely be more beneficial overall.
You seem to also miss that fact that there is sometimes both a relatively strong demand for a job and limited pool of applicable candidates (e.g., neurosurgery). That also drives wages up. It is a combination of the subjective value given to the deliverables for the job and the demand for the job. It is easier to replace a janitor than it is to replace a transplant surgeon. Additionally, the variation in performance from janitors is likely less than for transplant surgeons. This goes into the bidding of what people are willing to pay for such positions. It isn't anything against those who perform such jobs, it just is a reflection of how certain outcomes/deliverables are valued in a given society.
They don't.
I'm not sure what point you're trying to make by listing all these jobs salaries, but it sure does seem to prove mines: that all of this knowledge is out in the open so you can make an informed decision on your occupational intentions. Even competitiveness levels of each of these jobs can be found online.