Which is to say--narrowing things down--do the two actually have any mutual enhancement effect, such as, say, in the manner in which salt can fool the tastebuds into perceiving sweet as even sweeter? (thus reducing cost for sweetening)
I have never "observed" any such effect of salt and pepper used in tandem...at least I don't think so. Is it simply that the two are typically found together, and handily so, in most any food prep area? (The recommended reading elicited by the question suggests such an interpretation but does not address the aspect of s&p mutuality when shaken, used, or tasted together)
If there is, in fact, no such mutual complementary effect, it will suffice to simply say so--I will accept that as an equally affirmative answer.