I just read the link, Max, and here's what I think:

1. There is considerable confusion about Hindi being the 'national' language of India. It is spoken by the majority, but the Constitution recognises at least 18 'official' languages. English and Hindi are the two most commonly used languages; the former is the medium of instruction in most schools in a sizeable majority of urban and semi-urban areas and, also serves as an administrative and otherewise, link language.

2. Almost everyone (*everyone!!), in India speaks more than one language. In the South, that usually is three or four, because of the proximity of four states each with their own distinct language (Tamil, Telugu, Kannada and Malayalam). Almost everyone in the South (the urban/semi-urban South)can speak at least two of the above languages, in addition to English and a decent enough Hindi. The three language policy exists in different states in India, whereby, children learn three languages,- English, Hindi and a regional language in schools. In some states it is two, English and the regional language; Tamil Nadu is one such. But even here, schools that come under the central board learn Hindi. Hindi has made substantial inroads into the South, even if there had been strong opposition in the sixties to its 'imposition' on the local population.