Reality TV is cheap. In a highly fragmented and bundled market it can work. Yet, HBO and other premium services avoid it presumably because willing to watch is different from willing to pay for.

PS: Cheap TV can be compelling. Personally I really liked the primitive technology youtube channel which has 788,764 subscribers and is really cheap to produce 1 guy without any spoken lines. Twitch can also be extremely compelling. However, that's not paying subscribers.