It likely can't - videos are enforced as tap-to-play on iPhones, no matter what.
Which is good in most ways, but also means that people are converting videos into hugely bandwidth-wasting GIFs instead. I'd rather videos be "tap for sound" and autoplay at this point.
Hmmm. You can't assume the desirability of background video always correlates to use of a mobile OS. It correlates more strongly to related factors such as connection speed, battery vs AC power and CPU speed. My laptop tethered and away from mains probably doesn't want background video. A docked high-end tablet probably does.
Grandparent comment may refer to basically never wanting such video (which is my preference). In other words, the "feature" of the implementation being broken on mobile should also be ported to desktops.
If websites cannot act responsibly and make video and/or audio click-to-play[1], they are going to be added to the killfile. "Adblockers" are also useful for blocking annoyances[2], not just ads.
Which is good in most ways, but also means that people are converting videos into hugely bandwidth-wasting GIFs instead. I'd rather videos be "tap for sound" and autoplay at this point.