Criossants & sambar

I was listening to a rendition of an excellent song written by the fiery Indian freedom fighter poet Bharathiyar the other day. It was a fusion number and sounded quite fine till the girls started singing. They were mispronouncing all the words that had ‘s’ with ‘sh’ (Aasai was Aashai and Nesam was Nesham). This ruined the whole song and the experience for me. 
I mean if you are Sean Connery, I can undershtand you shaying thingsh like that but these were singers from the south (shingers from the shouth?). Even if you were not from South India, wouldn’t you learn to get the pronunciation right, no matter which language you were singing in? Can you get away with singing a popular English song on stage, mispronouncing all the words, saying shit for sit, shelf-control instead of self-control? How about the other way round, replacing 's' for 'sh'? Is that ok? Best wisses anyone? Nuclear fisson?  I doubt that.

Thing is, the very same people would go to great lengths to learn how to pronounce a foreign word, and mock you if you got it wrong. “It’s not Agnes B, it’s Anya Bay”, or “crosson’ not croissant”, they would say and still get sambar wrong. People who are from the North and West (and East I’ sure), always make it sound like you are eating idlis with a deer. That’s want sambar is (prounouced saambur). It’s an easy word to say, saam followed by baar. But no, we don’t mind butchering an Indian language as long as we get LanVin right.