Marketing surely takes advantage of it, but I think this has more to do with the addictive, yet passive nature of TV, where we let it push images into our brains.
My favorite example (for which I've already given away the punchline) is the following:
Ask a random group of people to imagine that they are watching a baseball game. Give them a minute to think about it. Then ask them -- Are you in the stadium? Or watching it on TV? The amount of people who visualize TV as their first reaction can be frightening.
I don't know that I agree with "frightening". I would guess people watch baseball games on TV much more often than they go to them, thus a question that asks about "watching a ... game" would trigger the more common of the two.
Your question is leading though. "Watching" heavily implies television. Being at the stadium involves much more than merely watching the game. I don't know of anyone who uses the verb watch in reference to actually going to an event.
That is where you and I disagree. I don't think the verb "watch" has any such inherent implication. Our society has given that meaning to the word in very recent times. Rather than dismiss my point, I think the modification of the meaning has proven it.
It may not be a modification. Did people even say "watch a baseball game" before television? Surely no one said "listen to a baseball game" before radio. What you've demonstrated is that "watch" in some contexts implies watching on a television. That's not the same as demonstrating the "addictive, yet passive" nature of television. It does demonstrate its pervasiveness, though.
My favorite example (for which I've already given away the punchline) is the following:
Ask a random group of people to imagine that they are watching a baseball game. Give them a minute to think about it. Then ask them -- Are you in the stadium? Or watching it on TV? The amount of people who visualize TV as their first reaction can be frightening.