(Personally I don't see any reason why GNU Emacs, when running
without windows inside a terminal emulation, should use other colours
then those I've chosen for the host, i.e. the terminal emulation.
Because it simply cannot know what you've chosen.
As I explained elsewhere in this thread, Emacs simply asks the
terminal to display color number N and _assumes_ that each number
corresponds to the color in the normal ANSI 8-color sequence. There's
no general-purpose API (AFAIK) to query Posix-standard terminal driver
for the actual colors that correspond to each color number.