One of the factors may be the fact that a lot of second generation Indian-Americans are mostly doctors, engineers etc. It is really in the culture to go for medicine, engineering and sciences as a career.

Within first generation, there is that segment of taxi drivers, gas stations, store owners as well but again, there is a huge entrepreneurial drive in those segments as well and many of them own their stores, gas stations etc instead of just working there. But then again, a lot of first generation Indians are also very well educated and they come for the STEM jobs as we all know.