I'm not sure why BG3 seems to want to separate Drow from Elves
I gues its bcs they have their own two sub-races ...
It would be weird to have them all in same folder ...
Also Drow have quite different set of racial bonuses. :-/
And from worldbuilding perspective ... yes we all know that "technicaly" Drow are elves ... but i bet neither group likes to hear that.

and Half-Drow from Half-Elves.
I dont think they are separate. O_o
Since first start of Early Acess they are both sub-races of Half-Elves ... only in pre-launch version, when Swen was playing, we have seen them separated.