But they do kill Superman in BvS. And bring him back in JL in a way that created a lot of narrative tension and audience emotion. And it was significant to the plot because it was the death of Kal-El that enabled the bad guys to risk going back to Earth again.
That is, IMHO, different that things like rewinding time or pulling in a multiverse version of a character because then it makes death TOTALLY meaningless and a lazy writing trick as it is far too easy to kill characters for a cheap emotional thrill just to 'fix' it a moment later.
Movies have a slow enough release that it is possible to kill main characters in a 'real' way for that cinematic world. Whereas comics have a monthly release and if the title of the series is "Batman" then, well, it's pretty much always gonna have Batman in it.
Comics do a bad job of having successor characters. They try but it rarely, if ever, sticks. So for the comics it is a perpetual whirlwind of false deaths, reboots, retcons, resurrections, etc. But movies can have a generational story, spanning 10-15 years and 10-20 total films, that do allow for a proper origin to death character arc with real stakes, tension, and death finality.