Why aren't Indian ETFs performing so badly relative to that nation's GDP growth?

The USA's S&P 500 [has averaged 12.65% in the last 10 years](https://www.spglobal.com/spdji/en/indices/equity/sp-500/#overview), and the [GDP has grown an annualized 2.5%.](https://www.statista.com/statistics/188165/annual-gdp-growth-of-the-united-states-since-1990/) The [Indian GDP has averaged about 6% year over year.](https://data.worldbank.org/indicator/NY.GDP.MKTP.KD.ZG?locations=IN), but [the ETFs that track their biggest and best companies from a broad range of industries has only averaged 8.2%.](https://www.ishares.com/us/products/239659/ishares-msci-india-etf) India's stock market should have about a 10% margin of performance better than their GDP like the USA, but instead, their stockmarkets are barely above their GDP for some reason. Their debt-to-GDP has been going down over the years, and moreover, their net exports will go up. **Why is their markets not such a great investment?** Also, **what is the best way to invest in a broad array of Indian companies?**