Salaries are set by supply and demand, and if there are plenty of people of Indian nationality who are jumping at the chance to work in California, then the hiring company is, on average, going to get away with a lower average salary. In much the same way that trying to get a Californian to go live in Mumbai, they may have to pay more than they'd pay a local, due to a shortage of people wanting to work in a city with clearly lower standards of living.
The problem here is that "Indian" is used English interchangeably as a nationality an an ethnicity, so there are sudden screams of "THAT's WACIST" from the overcompensating PC crowd. If they'd said "That's plenty for an English person", "that's plenty for a Minnesotan" or "That's plenty for a young unmarried guy", there wouldn't be such a problem. It's common practice for companies to end up getting away with lower salaries for people doing the same job, for a variety of reasons which are not protected in law.