Maybe we watch so much TV because we start to watch before our interested show is on, and then absentmindedly continue to watch after its over. Or how about channels that alternate reruns between two different shows during the late afternoon. To watch two reruns of a show you want to watch you sit through one episode of a show you don't really want to watch. Or how about that of the 157 hours of TV watching about 1/5-1/3 of that was sitting through / ignoring commercials.
I watch Netflix / Hulu / Amazon, etc... because of a few things. The ability to watch the shows I want, when I want. The ability to catch up on shows by watching a whole season, if necessary. The ability to watch old shows on my terms. And also less commercials. I'm not opposed to commercials, but they all seem to be either cars, car insurance, or feminine hygiene products.
I think Hulu only shows two 30 second commercials before or after a TV episode. Compare this to interrupting the show every 10 minutes for 2 minutes or so of commercials on cable / broadcast TV. And this is with me paying $60-$100 every month for the 'privilege' of cable TV.
I don't remember any commercials on Amazon Prime, but I may be wrong.