Har subah sirf utho mat Jaago Re TATA TEA

I am an Indian , an educated indian, wants to work in India for India, while searching for Job in Govt sect recently I saw an opportunity in Bangalore Metro Rail Corporation Ltd..I was shocked to see there notification states that -"Knowledge of Kannada is a must. ( The candidate should be able to Read, Speak, Understand and Write in Kannada)."
I can't understand why the government is applying these type of rules? BMRC is a Joint Venture of Govt. of India & Govt. of Karnataka,so why govt. of India is also accepting these? Does the efficieny of a engineer will increase if he/she have knowledge of a certain language? Is it fair to analyze a person's ability by understanding of regional language? Lot of people are working in Banglore from different parts of the country.They are performing extraordinary well without knowing Kannada.
I want to invite your views on this topic that why the people of this country are differentiate on the basis of language?
JAAGO RE!!!!!!!!!!!!!!!!!