Locally the talent pool is shallow, as most if not all the good engineers are well taken care of by their employers (as they should be).
If you're lucky you'll contact one at the right time who is looking for new opportunities.
If you're a Google, Amazon, or MSFT with deep pockets then you can pay to acquire talent. For others, it's not easy.
Have data to back up that statement?
That is the perception.
The reality is that there are a number of top engineers from overseas, and they are compensated very well. What India and China are able to do is produce a lot more average quality engineers. Indian and Chinese average engineers are on par with average engineers in the US.
There just happens to be a lot more average quality engineers from overseas then there are in the US. US companies have figured out ways to work with overseas shops that employ average engineers because the cost basis is worth it (1/6 the cost).
With programs like Code Fellows and other coding bootcamps, you're going to see an increase of mediocre American engineers, but at a much higher cost.