> The whole issue is specific to C and languages that copied C or use its runtime underneath in implementations (like Python)

So it's "specific to" almost all programming languages in actual use. That's a rather esoteric point.

> For reference, Unix has no API other than bytes either.

Unix does offer an API for writing C-standard in-memory text strings to Unix-standard on-disk text files, it just happens to be the same one as the API for writing in-memory binary strings to on-disk binary files.