Has it occurred to anyone that the reason there are so many former piano students (Suzuki-trained and others) that cannot sight-read, is that piano music notation is very difficult??!!! Think of it: 2 different staves (why couldn't they have been the same?), 15 key signatures, 5 accidentals, 4 sets of legerlines, many notes to be played at once, etc. I tell my students the truth - you will never be able to read and play any piano music like you read a book; it will always require practising to learn a hard piece of written out music! What can you expect, then? Well, you may be able to play some easy notated piano music at sight; you may be able to play from melody and chord symbols, you may be able to play some pieces by ear, you may be able to improvise, make up your own pieces etc. All this is possible if you keep learning and practising. I really disagree with the idea most teachers promote - you can become a classical concert pianist - what a lie!
Some pianists read better piano scores than books.
Why do piano have two staves. DUHHHH!!! MAYBE there are too many notes to stand on one, and it is more clear and easy to see like that!
And, in hell, WHY wouldn't some become concert pianists? You said like if NOBODY could. Some can.
In fact, a lot can,