I disagree that the notation is maximally efficient for expert users. Transposed notation does make it easier for expert players of the instrument to learn fing

I disagree that the notation is maximally efficient for expert users. Transposed notation does make it easier for expert players of the instrument to learn fingerings for multiple instruments, but as zozbot123 mentioned, the notation makes it harder for expert readers of sheet music to read a score for multiple instruments and imagine the resulting sounds in their head. I think a maximally efficient notation would not have that drawback.