Why is it that the programmer X is paid 10 times less than programmer Y.
First, I think it's an oversimplification of the U.S. to overlook that salaries vary widely here as well. Someone in NYC or SF may make 2–3x that of a person in a similar role in a small city. And a very senior person on the coasts can make 5–10x what a junior dev would in a small city.
Usually when authors compare figures in articles they attach to the coastal numbers instead of giving more honest comparisons by city or state.
Another factor is cost of living. $150k in SF sounds like a lot of money but roughly half of that covers rent, transportation, taxes, etc. Healthcare is very expensive here too. In SF or NYC, food is expensive as well. In some countries, $15 covers enough food for the day or more, in SF that might cover lunch.
One more is that the demand for good experienced programmers in the U.S. outweighs the supply for various reasons. We have the biggest tech companies in the world, so Google for instance can afford to pay hundreds of thousands of dollars per year to retain the best talent since they make roughly $1M in revenue per employee.
http://www.businessinsider.com/revenue-per-employee-at-apple...