Your numbers must be pretty outdated for Rails people (or maybe you don't recruit into well-paying gigs) if you think those figures are well above what we're making. I'd say most salaries are comparable to that.

And I think you're probably right for PHP and Java. The talent pool is saturated, so there's little "demand" for that sort of employee. "Oh you want $70k? Sorry, we've got 10 candidates who will take $40k. Bye!"

But outside of the markets you specify, I think the same situation exists for .NET developers. I know a good number of .NET devs who work in government contracting work and make about half what you say they should make. I know a few who work for product companies in towns other than the ones you mentioned that make about half also.

It's probably different markets, business models, but let's not act like .NET is some magical cornucopia of money that will shower you with many monetary blessings if you just sell out to it (this coming from someone who worked in .NET from its beta until right after 2.x came out).