If we were approached by aliens in a starship, we can be sure sure they would observe us closely and try to learn all they could about us before their first contact. They might well focus on areas of the globe that glow at night, since those areas are probably more suggestive of some form of civilization than are the darker areas. Quite possibly parts of the the US of A (Our Fair Country©), either coast, or other parts of the country more densely populated than, say, the Grain Belt or the Rockies.
Their sensors would doubtless be quite advanced, and would surely pick up all of our electromagnetic radiation from the myriad of devices and equipment we operate that sends broadcast information to other equipment. Cell phones, aircraft, surface ships, and even the tiny transmitters embedded in our currency (allegedly) and our passports (for sure) contribute to the cacophony the aliens would receive.
Out of that mass of noise the aliens' advanced receivers would be able to isolate signals by frequency and source. This would not require much advanced technology: today almost anyone with an appropriate receiver can distinguish between channel 2 and channel 6, and my T-Mobile cell phone does not conflict (much) with other T-Mobile phones operating in the area. Eventually the aliens' analysts would likely hit on our television broadcasts, as these are intentionally bounced off satellites, and likely "leak" into space beyond the targeted satellite.
Now imagine the aliens can see not only the images and sound that go with a given broadcast source, but also, through alien magic, they can also observe the terran life forms' reactions to these broadcasts. Here's one of the observations: the terrans (let's call them "viewers" for short) stay in one part of their dwellings observing the decoded visible and audible signals. These signals have two distinctly different modes. The first is what is termed "content" and is distinct because the broadcast of this "content" seems to flow from segment to segment, and is interrupted at intervals by the second mode of broadcast by "messages".
The aliens notice that the "messages" convey orders or directions that the "viewers" seem to understand and seem inclined to obey. This compliance with the directives in the "messages" puzzles the aliens, because the "messages" themselves seem to offer no legal or regulatory basis. The "messages" just say "Go do...." and the "viewers" do just that.
Alien psychologists are brought in to resolve this seemingly irrational behavior, and after a few months of observations, conclude that the purpose of the "content" part of these broadcasts is to put the "viewers" minds at ease, to stimulate the emotional part of their brains and to suppress the rational part. Their analogy is to the process of hypnosis, in which the hypnotist has the subject focus on something mindless (like a crystal bijou swinging on a chain in front of the subject's face) and, speaking softly and soothingly, fills the subject's mind with relaxing images - a seashore, a field of flowers, a babbling brook. When the subject is completely relaxed, the hypnotist suggests to the subject that he or she believes something, or will do something after he or she awakes from the hypnotic trance. And once awake, the subject does what he hypnotist suggested.
We know that hypnosis works with many people. It is used in therapy and in other applications (see linked article). Our alien psychologists know of this, naturally, and their studies of "viewer" behavior on this planet confirm that these broadcasts are, in fact, hypnotizing the "viewers" and causing them to accept the beliefs and perform the actions as directed by the "messages".
The aliens marvel at the ingenuity of the terran life forms (call them "owners") who invented and control this method of controlling the other life forms on the planet ("viewers"). Having discovered that this hypnotic method is effective, the "owners" first priority was to inculcate the belief that "viewers" need to view. "Viewers" need to spend their own earnings in order to acquire the necessary equipment to receive the broadcasts, and further, they need to spend ever more to ensure that the quality of the broadcasts is as close to perfect as their primitive technology will allow. Ingenious!
Next, the "owners" focus on increasing the level of compliance of the "viewers" with "content" that is ever more relaxing, and requires as little thought as possible. The ideal "content" is that which has the "viewer" with a completely open mind, ready to receive and internalize the block of "messages" the "owners" send next.
And that, the aliens discover, is how broadcast media came to be the perfect way for the owner class to dominate and subject the viewer class, and why the viewer class "needs" bigger and better TVs, cable or satellite broadcast, and even areas of their homes dedicated to receiving the messages and doing what the messages "suggest".
If you, the reader, watch television, you are a "viewer". It is certain that you will obey the "messages". You can't help it. Now you know, and you know why. Are you going to do anything with this knowledge?