Linux kernel design patterns - lack of red/black tree search function

Yes: and if the compiler was sufficiently clever, and all the .c files in
the application were presented to it at once, it would recognise instances
of this function that were frequently called with a particular function
pointer and clone a variant of that function that had that function
inlined into it: said variant would then get used only by the particular
call site in question.

This is way beyond what, say, GCC can do now, but is not disallowed nor
impossible to implement.