This is particularly true in post-COIE, when Clark has no attachment or memory of that name. At least in the silver age Superboy he thought of that as his real name sometimes - not the case later (or earlier).
I don't mind it in private (at a certain point, they have to just hope it's safe, or else they couldn't even change clothes from one identity to the other without fear), but in public, it is annoying. It's been that way for a while, true. Since the '90s, at least. Haven't paid enough attention to see when the trend started, though.I'm the opposite of that one. I absolutely can not STAND when actual experienced professional superheroes call each other Bruce, Clark and Hal... WAY too many ways for people to be spying on them... anything from mystical to satelites that they could never be sooooo 'flippant' with the secret identites. It's definitely a trend of modern comics that I hate.
To me, it makes much more logical sense for them to just call him "Superman" in that case, rather than "Kal".'Kal' is the one thing that i do make an exception for.... since Kal is a non-entity. Kal-el has no loved ones or employment or a street address to blow up. if Lex or Brainiac learn that Superman's 'real name' is Kal-el.... it gains them nothing. So I can cut that identity a little slack. But Clark and Bruce... ughhhh... That's just rookie moves.