English is widely used throughout India, as it's the "national link language" according to the constitution. Most advertisements, street signs and stores contain lots of English.
I've never been to any other country where mastery of a national language was as poor as English in India. This goes for both written and spoken language.
How many countries have you been to where there are 20+ "official" languages ? The point is that English (even though official) is not the only language of importance and most states/regions/cities have their own languages that are spoken . English glues things together but more like a duct tape. Hence, a lot of people (specially the poor) don't learn English as part of their daily curriculum and that really varies depending on the region.
