That's like comparing apples with oranges. Sun Direct is not even available pan India, they have their own downsides which they are balancing by offering discounts. Any company will adopt such strategy to survive in market, if your services are not equivalent or better than competition they you can't charge full price from your customers. Leave other things, just check how many total channels they carry. Number of only SD channels on Tata (521) is greater then all combined grand total of Sun (466)