Probably because Humans are so common and vanilla in the entire world that no one is phased by their presence for the most part, ergo no reaction to them.
More like bcs Humans dont have enough common signs ...
You know what i mean ... Human from Sword Coast is not the same as Human from Wild Coast, wich is not the same as Human from Dragonmere, wich is not the same as Human from Moonsea.
(I dont even know if there is any humans setlements, i just picked some locations from
here)
Also keep in mind that when you play human, you are from Baldurs Gate, every dialogue options you have bcs of that is hidden behind [Baldurian] ...
Wich also have Dwarfs, since they are also from Baldurs Gate, but also have differend Dwarven herritage, since every dwarf is commonly known as miner and crafter. Wich is what Humans are simply not, bcs they all are sooooo different. :-/
Therefore i dont think that you see condition [Human] before dialogue options, bcs there is little written to them, but bcs there is so little to connect them all. :-/