The same thing exists here in the US we just don't have a name for it. It's just 'cost of living adjustments'.
Being in Construction, if we hire a heavy equipment operator (we build roads) for a project in California we need to offer him a higher wage (we also have to abide by prevailing wage laws) than if we hire him for a job in North Carolina. This even applies to existing employees. If a Project Manager takes on a project in CA he gets an increase in salary, if his next project is in Georgia his compensation is adjusted accordingly.
Biting the hand that feeds IT
