You sure? I just did a quick search for EE salaries in London[1] compared to Detroit[2] (the closest large city to me) and Detroit comes out ahead by a lot. And I'm sure rent is cheaper.
However, I agree that salaries are ridiculous in some cities. I'd love to give living in NYC or LA a shot, but the salaries I see for EE jobs are marginally more than what I make in the middle of nowhere.
You're right. Detroit is higher than I expected. I guess low GBP rates make a difference, when I was in London 1 GBP = 2 USD. (Rent in London is definitely not cheaper.) London isn't a great place for EE. Software in Banks had/has crazy demand.