alt Hacker NewsI can't speak for all South Asian Americans, but in my experience caste is not a significant player in our community in the US at least.
Alternatives like University Affiliation, Regional ties, Ethnic ties, Clan ties, and Workplace affiliation play a greater role due to the nature of South Asian immigration in the US (tends to be white collar professionals across all ethnic groups).
Treating South Asian Americans homogeneously will lead to the same mistakes like treating all Latinos homogeneously - plenty of South Asian heavy battleground counties like Loudoun County, Middlesex County, Williamson County, Kern County, San Joaquin County, etc have seen Ds margins drop significantly in the current election.
That said, we are a clannish bunch, and biradari (and every other South Asian language's equivalent of that word) is our guanxi.
Kern and San Joaquin in particular are the exact opposite of white collar professional immigration and more similar to Guyana. (My great grandfather came during that 1920s era but jumped ship in NYC instead) People often forget some of us came before 1965. Vivek Bald has an excellent book about it.