Trai — should we pay for paid channels if they telecast advertisements?

All the paid channels are telecasting n number of advertisements. Then why we have to pay monthly fee for them? If it's a paid service, isn't should be advertisement free?
If they are telecasting advertisements, then the channels will be getting paid from the ad-vendor. Then why the subscribers has to pay them monthly charge for each paid channels.

Paid channels should be giving the channels at 0 cost of they telecast