Languages of India

It doesn't. That is the reason why you see so much bloodshed with one side trying to overpower the other. J&K is not homogenous. The Jammu part is majority Hindu and Kashmir part is majority Muslim dominated (it had a minority Hindu population too called Kashmiri Pandits but they were raped, murdered and eventually driven out by the majority. Read up on "Exodus of Kashmiri Pandits": https://en.wikipedia.org/wiki/Exodus_of_Kashmiri_Hindus). The Muslim dominated part wants to break away from the "Union" and form its own Country. Do you see what I have been hinting at? The religious division that was created when India was partitioned continues to plague Indian society even to this day. Now you want the Indian society to somehow forget and forgive all these issues and just join into a bigger Union with states that were created with diametrically opposite ideas? That is impossible! Why would Indian taxpayer want to carry the burden of states that have a hatred for Indians?

> After all, people of this region have so so much in common. Plus, in such a union each "nation" would retain it's identity while having extremely close ties to other "nations of the union" e.g, free trade, travel, etc.

I appreciate your desire for unification on a common ground and I wish for it too. But that is not a probability because of religious intolerance. You can bury your head in the sand and choose to look the other way but that is the reality. Until you have religions that believe that theirs is the "true path" and the rest will go to "Hell" there is no way we can achieve any sort of common ground. Reformation should happen first. Some sticking points that exist in each religious denomination should be discarded as being irrelevant for today's day and age. Now that is very much possible. Hinduism has undergone various reformations over the ages and continues to do so. Sati system was abolished. Caste system that discriminated has been upended by a Reservation system that uplifts the socially deprived. Sure it is not perfect yet but it shows positive intent. But these reformations cannot be a one-way street. If such similar reformations happen in all other religions then you would automatically have unification. If you are only looking at economic/political advantages then that is a poor solution that is bound to fail. Unification should only be on mutual-respect for culture, tradition, religion, creed etc. Things that have real social value. Not money or politics. The former will cement the Union, the latter (example: EU) is a weak foundation that will eventually crumble.

I am not Indian, so please correct my outsider's perspective if it is wrong, but from what I have seen, this is mainly believed by North Indians, and often deeply resented by South Indians, who are more likely to view English as a common, neutral, pan-Indian lingua franca, and Hindi as too North-centric to be appropriate for that role.

What are those? It is just a language people speak.

* Large parts of the US provide ballots and other voting materials in Spanish (or Vietnamese, or Chinese, or various Native American languages, ...).

* Courts in the US will go to pretty extreme lengths to find interpreters for criminal defendants who can't understand English, even if their native language is somewhat obscure.

* There were public schools teaching primarily in Spanish until at least the early 2000s in Arizona; not sure if they still exist in other places. There are definitely still private schools teaching in non-English languages in some parts of the country, particularly Yiddish.

Anyway, making explicit any link between citizenship on the one hand and language or culture on the other is considered a somewhat solidly right-wing belief in the US (and I would expect in other countries that began their history as settler colonies, like Canada or Australia), whereas it would seem like much more of a centrist consensus in even some overall more progressive-leaning societies (from Article 2 of the French Constitution: "The language of the Republic is French". I would be shocked if France lets you vote in Arabic or teach public school classes in Lingala).

Because it's perceived as solidly right wing, and the other side of the political spectrum will fight it tooth and nail, it's hard for me to imagine the US declaring English as a federal official language in the foreseeable future.