The most striking thing in that data for me is how low India is.

This includes only diagnosed cases of colon cancer, so if India has much less screening and fewer diagnostic opportunities, that will greatly reduce its score. But it is still a striking number!!

I have no idea if it makes a difference in reference to the study, but plant based diets are significantly more common there.

What data? The article only seems to be about the US?

Indian diets are very different from the average American diet. Loads of vegetables. Even non-vegetarians get tons of fibre and are often eating 20-30 different plants in a day. Most of it fresh too.