Why are the three flights (see image below) not using either Nepali or Bangladeshi airspace? The five "freedoms of the air" should have allowed them to follow a more straighter path, instead of burning so much fuel, at altitudes of more than 30 thousand feet.
Some countries have more strict rules regarding their airspaces - Nepal and Bangladesh are among them, requiring special permissions even to fly through it.
Though possible, it might not be worth the hassle and the costs - this small detour would only require very little fuel.
For Bangladesh this is even more strict, as there seems to be an active ADIZ: