A belated welcome, @Clamshell! I’m curious where you tried these dishes, and where you are located.
I’m Indian, and I’d like to go to Kashmir. It’s the one cuisine that is very hard to find (in other parts of India, never mind outside the country 
), and rarely done well.
Even in India, for a long time restaurant food meant North Indian / Punjabi / Mughlai. In NYC where I am, Indian food is still more likely to be that, or then Pakistani/Bangladeshi. Recently there’s been growth in Nepali-Tibetan outlets given the immigration patterns.
The challenge for Indian regional cuisine is that you need someone from a region willing to cook the food professionally, and there was little interest that as a career path.
Another hurdle is customer palate. You can’t go to a Chettinad restaurant and still expect to order tikka masala- it’s like going to a French bistro and wanting Danish food. But that’s what happens. As a result, we have “South Indian” restaurants that serve full North Indian menus. “South Indian” itself being a too-broad bucket for anywhere that serves idli-dosai, even though the south of India encompasses a variety of cuisines, with distinct meat-eating and vegetarian traditions.
But I’m encouraged by the increasing diversity of regions represented by newer restaurant menus and chefs showcasing regional dishes.
It’s like the growth regional chinese food - once you’ve been exposed, you want more of it, and when customers are looking for something different, restaurants that service that can survive.
