I am not sure if H1's are paid any lesser than locals...Do you have data points to prove otherwise?
For example, many US companies are created by immigrants (18% of Fortune 500, or 40% if you include children of immigrants). Steve Jobs was the child of an immigrant. Hiring a guy who is so enthusiastic about getting a job that he wants to live in a rural area and live on a pittance, vs hiring someone who's ambitious and hungry - who's going to create the most value?
That said, it's prone to abuse and I have seen some H1s with really poor compensation due to a weak negotiating position (the difficulty of switching jobs while in-country, sponsored adjustment of status, etc.).