Getting less for more with traditional TV

When browsing around iTunes, I saw something that I was shocked by at first. Since most of the TV Shows I have bought are all from the modern era (00s on), I just assumed that commercial-less shows ran about 44 minutes, like Star Trek Enterprise:


But then I saw that older shows actually have a runtime around 50 minutes, like Star Trek The Original Series Remastered:


Let's review. When viewers sat down to watch the episode Where No Man Has Gone Before of Star Trek The Original Series (I picked the Remastered links, running time is no different) on broadcast TV it was free to watch as long as you sat through 9.5 minutes out of 60 watching commercials, between 15.8% of the hour. Not too bad. When watching Broken Bow, Pt. 1 of Star Trek Enterprise, 15.5 minutes out of 60 were dedicated to commercials, 25.8% of the hour, a 10% increase in commerical time over the original Star Trek, even though you were most likely paying for UPN, and thus the show, either through cable or satellite TV. The only real mystery here is why people have accepted the errosion of actual show for more commercials while always paying more for TV?