In India,pay channels has more ads than FTA channels in most cases(Eg:Sun TV, Asianet etc during movie premieres).Why we pay for the pro version of softwares or apps? -one reason is for not showing ads. But in TV channels its arbitrary.
Unfair comparison, in foreign countries subscription to channels costs multiple times than what is here in India hence in former case broadcasters don't feel much need to be dependent on ads for revenue.
Coming to ur 2nd point about pay channels showing more ads in India than FTA ones, well again u cannot expect them to be ad free bcoz of reason i mentioned above. Also see the difference in content u get on a FTA channel vs a pay channel, producing content or acquiring it is a expensive affair & pay channels need to show more ads to recover massive investment & achieve profit. FTA channels mostly air repeat or produce/acquire low budget things hence able to manage well with limited ads