Firstly they never say "Indian Restaurant" but "Pakistani, Indian and Bangladeshi cuisine".
This is what Indian does too. Grocery store, restaurant, etc. It is called business move. I've saw many Pakistani restaurant with "We serve Pakistani, Indian, Chinese, Middle Eastern food". This is purely business move.
I've saw one restaurant, it's name is after Pakistan's Khyber pass, it's owner is Afghan/Indonesian and it says "Indian, Afghan, Pakistani, Indonesian food". When I went there I failed to find any Indian or Eastern Pakistani food. All they serve was Afghan, North West Pakistani, Indonesian food.