Yet in reality, nobody actually needs a name that's sorted by surname: that's a holdover from paper phone books. We have search, and we have stable sorting algos. Every requirement "sort by surname" I've ever seen turned out to mean "sort the names in a predictable way, btw this is the way we always did that, because we always did that."

(Yes, familiarity is a part of UX; but do note that this one specifically is a historical, not intrinsic, motivation)