Sir, exclusion due to a different language isn't a problem unique to only Tamilians or other South Indians. I have stayed in Chennai for quite some time and a common pattern that I've noticed is that people pretend to not understand Hindi or even English if they find out that you don't understand Tamil.
I was left stranded at 3 Am on a dark highway by a rickshaw driver once, and when I tried to talk to the guy he didn't reply in Hindi or English but to hurl abuses the guy happily yelled 'Bhenchod' and 'Bhosdika' only because I refused to pay the full amount because he didn't drop me where he was supposed to and I was still 30 kms away from the destination.
I didn't expect a response in fluent Hindi from a rickshaw driver but basic words could've really helped in that situation.
Fun Fact: I have learned basic words and phrases like Thanni venu, Evalo, Tamil Teriyad, etc in Tamil to be able to communicate.