The thing that really just pisses me off to no end about secret identities is the heroes constantly having to lie to their loved one and sneak around. It just leads to a lot of stupid, annoying, pointless drama with everybody constantly getting pissed at them for not being around. That kind stuff always annoys me, even it it's not superhero related....which makes Lana an unnecessary liability not only to SM, but to his family. Again, there's no point in the hero revealing his identity to civilians, just as its dangerous for villains to learn those secrets. As it stands, Alt-Jonathan kidnapped Lana not because he happened to see her run into Clark on the street, but it was due to his knowing Alt-Lana's relationship to his own father, and simply used that information to exploit / lure SM into a trap.
Some of comic books' greatest stories involved the danger and sometimes lethal consequences of others knowing the hero's true identity, ever proving the point that being a superhero is not some club for the needy to feel they must know everything about another person (when its not their business). Further, the notion that the civilians can "prepare" for the dangers in the hero's life is patently absurd and incredibly unrealistic. They are regular people living regular lives. They are not on call / high alert in their lives and no rational mind would expect them to be. Moreover, they are not even on the level of non-super-powered fighters such as Dick Grayson or the Punisher--meaning they have no way to "prepare" for high level and/or super-powered threats.
There's absolutely nothing a civilian can do if for example Darkseid, the Green Goblin, Doctor Doom, Mister Freeze, the Mandarin or anyone else comes a-callin' for said civilian, which the comics have proven in the most tragically memorable ways.
Well observed. Real human being seem to know that there is a natural reason for separating parts of their lives (particularly if there's an element of risk involved) from the people they know in their private life, as there is always someone ready to exploit that knowledge, and for the superhero, his life is so dangerous--always threatened by the most relentless of foes--that they would not hesitate to harm someone known to be in his private life...which is exactly what happened to Lana in this latest episode of Superman and Lois.
Clark was badgered by his kids into giving in to their inexperienced "wisdom" and exposing himself to another. If competent writers were handling a plot of this kind, there would most certainly be a price to be paid for Clark being so thoughtless, and adding a new layer of danger to his family.
Once the people know, at least then can understand that they're literally off saving the city or world or whatever, and should hopefully be more understanding.
And really, as long as they're careful, and the bad guys aren't aware of their connection to the superhero, then I really don't see where they'd be in any more danger than they already were before they knew. The thing that really makes a difference if the villain knows, and if they know, then it doesn't really matter if the loved one knows.