[rushafi]

I think you should rephrase like this: iOS developers these days, "who lives in USA" and are experienced (eg: over 4 years experience) should make $150/hour as contractors.

In Toptal the pay varies on developers and client's budget. I think the lowest rate the companies have to pay in Toptal for a full time developer is $45/hour or $1800/week (highest can be $3200+/week, ref: http://www.toptal.com/faq#how_much_does_toptal_cost). Toptal has more or less a 50% markup over what developer gets. So given company's budget and preferred time-zone to work they try to match a developer whose pay will fit within 66% of clients budget. And you can be sure of the fact that this 66% is a very handsome money for a lot of developers worldwide considering the living cost in their country.

I can assume that even the highest range Toptal offers might not be good enough for Top 3% US developers. But it's good enough for Top 3% worldwide developers who has accepted into the Toptal network. Also why on Earth developers in the US will have to rely on Toptal or other similar sites? Definitely they can access the jobs more easily than a Eastern European / South American / South East Asian developer. Don't you think so?

Finally, who are pointing on the fact that developers, despite of their nationality, should get the same payment should also consider that Nationality is not the main issue here. People who gets migrated to USA charges the standard rates in USA. But who are not living there don't need to charge the same because their living cost is much less.

(In short, if your expected payment is above than what Toptal offers, don't apply there. Toptal is very good place for freelancing jobs for a lot of international developers, but it's definitely not for everyone. And the fact that, its not for everyone doesn't necessarily make Toptal a bad thing).