I'm not talking about the killing, at least that is not the main point. Having him kill Zod to keep that one family from getting murdered, when Zod & his followers had just killed thousands and this version of Superman didn't lure them away from the freaking city, makes literally no sense. Though, regardless of what they originally did with the characters in comics, you have like 50+ years precedent where he DOESN'T kill. Batman, too. And it's a moral quandary because there have been multiple stories showing if they had just killed the particular villain, then more people wouldn't have died. "Cross that line and I will become worse than the villains I fight." The current model, comics or film, doesn't work because no one is buying the comics/watching the films. It's agenda-driven garbage written and drawn and filmed by people who hate their audience, and the audience responds to that. Rebirth brought a big boost to DC, and introducing the original, decent Superman back energized readers. They even, through Wally's monologue in DC Rebirth 1 as he was trying to reach out to people from the Speed Force, showed they realized the fans didn't like the way the heroes were being written. Sadly, that only lasted a few years before they forgot about why people came back to reading their comics and the infection that ruined it in the first place took root again.
Back to the movies, Johnathan Kent was done super dirty, too, by Snyder. Having Pa Kent tell Clark he should have let people die. Then, letting Clark watch him die when Clark knows he could have saved him, not caring what it would do to Superman's psyche, is pure evil. In the comics, Pa Kent dies in different reboots. But it's almost always a heart attack or something similar. And there is a reason for that. It is to show that there are some things, no matter his godlike abilities, that Superman simply can't win against and there are just some people that cannot be saved. He is, in fact, not a god.
Trying to put realism into a superhero movie is just a dumbass proposition in the first place. (Joker wasn't an actual comic book movie.) You're absolutely right, Superman and Wonder Woman, hell even Flash, would be killing pretty much every person they fought if real world physics applied.
Don't get me wrong either, I like Elseworlds stories. The Injustice games and the accompanying comics are awesome and brutal and heartbreaking. I loved them for what they were. The problem is, even as an Elseworlds, Snyder's movies are an incoherent, headscratching mess. The whole way Doomsday came into being was just plain stupid. Batman and Superman fighting in the first place because of the reasons Snyder set up was completely idiotic and makes both look weak, stupid and unworthy. For his version of JL, somehow Darkseid remembered he got his ass handed to him on earth and lost the mother boxes there but forgot that earth is the location of the thing he has been searching for his entire existence? Superman flies off fast enough to create a sonic boom with Lois in his arms? Wonder Woman blows up half a building to take out a single bad guy, not caring that all the police and bystanders under could/should be crushed by the falling rubble? Also, Superman is weak to magic. How did he casually shrug off Wonder Woman's lasso? There are many, many more egregious decisions Snyder made but those are the ones right at the forefront of my mind atm.
Again, I am saying I don't think Snyder actually ever read the comics, at least not any before or after the New 52. He sucks. I get that people like him, though I can't see why personally because most of his movies are just not good - and he loves his slow-mo like JarJar Abrams loves his lens flares. I just can't stand him. I have always been way more of a DC fan than Marvel (X-Men being the exception and Marvel fucked them 7 ways from Sunday in the comics and movies) and I just hate what he and Warner did to the characters and mythology.
Though, like I wrote, with JarJar and his franchise-killing touch, along with his woke agenda (his wife was a key person in the poundmetoo bs), it's only going to get worse if you are a DC fan like I am.