The US developers, though only a year or two out of college, easily outperform even the "mid-level" developers from India. The price our company pays for Indian developers is about 1/3 the cost of US developers, but so far, we have not been able to make the math work. Even 3 Indian devs cannot produce the same quantity and quality of output as a single junior US developer.
If you're paying the Indian developers 1/3 the money you pay US developers, why not simply hire European developers for the same cost...?
Probably because there is not the same level of infrastructure around offshoring to European developers. I work with an offshore team, and the entire company there is dedicated to working with US companies. They skew their working hours to match the US, they market themselves in the US, and they train their staff on US specific rules (such as HIPPA or PCI) so that they can provide people that are useful.
If I wanted to replace my Indian team with a group of Polish developers tomorrow I suspect I would have a much harder time finding a similar provider.