Compared to FTE the difference was even larger including benefits and vacation time.
The biggest issue though, is not the local people. The issue is that the local people are there to bridge the timezone and communication gaps so you can have three off-shore people for each on-shore. Offshore people were paid less than a third of on-shore. So the number of American jobs they are displacing, and the wages they were being replaced at, is absolutely staggering.
Maybe in real tech companies its a different story. The one time I did a direct H1-B sponsorship (later, in a much smaller company), we did pay them an equal wage.