It's not exclusive to India actually.
Here in Japan there's 1 language, but culture differs per city, prefecture, and region.
There's eventually a huge cultural rivality between the Kansai and Kantou regions.
Both regions have their own dialect-specific vocabulary (though most are vulgar and/or slang).
An example in cultural difference would be that people from Kansai go to bath straight away, while in Kantou people shower first to make their bodies clean first before going to bath.
It even goes as far as both regions having different TV stations, and one region cannot access the channels of the other.
So if you live in Osaka and want to watch TV Tokyo, then too bad, you can't!
And there are people who would spend lots of money and time for a bullet train to eat Tokyo Banana, which is a snack only available in Tokyo.