The higher end in London is substantially more than that across banking, insurance and foreign tech companies and contracting day rates were really rather good. Admittedly I’ve been out of the U.K. for long enough to see what impact Brexit has had, especially on contracting day rates.

Still nothing like the US though, and the cost of living is not much different than New York City IME.

While most software engineers in the U.S. don't make 300-400k, you will make above 100k pretty quickly. You can make 150k-ish total comp at tons of places in the United States. These places will usually offer very good benefits too.

No it is the international investor effect. People do not invest locally. The money goes to a few proven places rather than circulating throughout the entire country.

You can call the investors kings and the workers are chasing the kings money.