Except for Netflix which is $8/month, rest of the streaming services are very cheap. Hotstar has content from HBO, Showtime etc. Amazon Prime is ok. There are lots of Indian streaming services with Indian content. A lot of data consumption in India is video content hosted within India.
Not comparing the content library, but the cost here. Netflix is not very expensive compared to Hotstar or Prime. The latter two are targeted at family watching. They don’t have the concept of user profiles on a single account. If you have a family of four with each wanting to watch something different without trashing others’ watch lists, progress, etc., then with Hotstar and Prime you’d have to buy four separate subscriptions. With Netflix, you get five separate user profiles for one price.
Also, the quality of video and the user experience on Netflix is leagues ahead of Prime and Hotstar (in that order). Hotstar is very poor on technology and design. It only has its content catalog to lean on.