Subscriptions mean you have to pay a certain minimum amount, even if you want to watch just one episode of something. That's a much bigger burden than changing the channel.
Yes, in theory you can carefully manage things and cancel as soon as you've watched what you wanted, but in practice that effort is a cost too (like watching a commercial is a cost).
This is an opportunity cost but only if you have the stamina to be doing billable work during all that time instead of relaxing.
Commercial detection and skipping has worked well for me via MythTV for nearly twenty years at this point.
Seems like there’s a free startup idea in there somewhere. $100 worth of equipment and a webapp and now your parents can watch network TV, local news, sports, and weather without ads.
At a labor value of $50/hour, watching ten hours of content a week imposes an economic cost on the viewer of $825/month. By comparison subscribing to all the major streaming platforms would cost about $100/month. Let's not even get into issues of higher quality content and huge on-demand libraries. It's pretty clear ad-free streaming subscription is a massive improvement for consumers over "free" broadcast TV.