Because american workers don't have unlimited rights to immigrate to india.
Because the cost of living here is much higher. A person will starve to death on the same salary that would be excellent in india.
Now, IF capitalism were allowed to work and we could buy products from india at the prices indian consumers pay- that would help a lot. But we have artificial laws preventing that.
Flatly ILLEGAL web sites offer the same drugs for sale from india at under 1/4th the cost the same drugs are sold in the U.S.
Microsoft charges U.S. citizens over $1,000 for the same products they give away free to indians.
It's a short term problem. It's going to resolve itself and indians are going to experience tremendous inflation while u.s. workers stagnate until automation wipes them both out.
And then it will be very stark. Some people will have money and the majority of everyone else in the world will have no way to trade their labor for money