yeah, I've noticed.. sure its tasty, just different, they have their own takes on it, which is fine.
wrong about not getting authentic southy food in Dilli at least, there's lots of super authentic ones with staff packed to the brim with proper southies. cooks, waiters, everyone.. there's the legendary Sagar and Savarna Bhavan for veggie udupi dosas, filter coffee etc, there's Swagath for malabar and southern seafood and others. There are still nooks and crannies where we get beef tikkas etc too but they've gone slightly underground after the current guys came to power..
pata hona chahiye, sab kuch milega