To try to understand phonetics vs. phonology, I already read What's the difference between phonetics and phonology?, Oxford Univ. Prof. John Coleman's page, ResearchGate, Univ. of Pennsylvania Linguistics, Quora, SUNY at Albany's summary.
Please see the "phonemic" that I colored in gray. If the author wrote "phonetic", would that sentence still be correct? Why didn't the author write "phonetic"?
14.1 Phonetic, Semantic, and Glottographic Writing
Language is a relationship between sound and meaning, and it contacts the real world at two interfaces; phonetic and semantic. In principle, we can represent an utterance by writing at any of these three levels: phonetic, linguistic, or semantic.
We are familiar with the notion of a phonetic writing system which could be used to transcribe the sounds of any utterance in any language in the world; such a system would be similar to the International Phonetic Alphabet (IPA; see Appendix B and International Phonetic Association 1999), which provides an inventory of symbols for a wide variety of phonetic phenomena which occur in human speech with certain rules for using these symbols. The symbols represent pure sound and are not associated with any particular language. That is, the IPA provides symbols sufficient to represent all those phonetic distinctions which are contrastive in some language somewhere. However, as MacMahon (1996) notes: 'Strictly speaking, then, the IPA is not a universal phonetic alphabet in the sense of an alphabet that will provide a notation for every conceivable sound used in a natural language. Rather, it is a selective phonetic alphabet which is constrained by the requirement of
phonemiccontrastivity.' Even though the IPA may not be a completely phonetic writing system, it is clearly a close approximation.
Henry Rogers, Writing Systems (2004), p 269.