But it's weird and unnatural for substantially different reactions in tone and content to lead to identical reactions from others.
Not if the reaction they lead to makes sense in some way for all of them. Granted, that's not always the case, but people certainly can react in the same way to a wide variety of different things. It's also not something that tends to really jump out, as you don't see the same reaction to different things one after another, rather on each different play through the game.
I recall from previous iterations of this topic that you're a lot more particular about NPC reactions to dialogue than I am, though, so this may simply be a difference of opinion.