Bazza1
macrumors 65816
Because an ad agency and its client doesn't need to create an ad for a product and a broadcaster doesn't need to look around for ads to pay for the airtime. A subscription means you're doing the work for the broadcaster.there are no ads on Netflix and Amazon Prime video plus.
Radio and television were both created to act as an advertising medium - companies paid broadcaster (and in some cases, stations were created by advertisers) to air ads. The programs themselves with the interstitial bits between ads, used to encourage folks to stick around to the next ad. Now we think of the ads as the interstitial bit.