Nib asked, and Nib — askNib's tutor — drew the answer live at a whiteboard. This is the spoken transcript; enable JavaScript to watch it drawn.
Why can't AI count the r's in strawberry? (for a curious adult who uses chatbots but has never studied computing). Cover, in this order: What does an AI actually receive when you type a word?; Where do tokens come from?; Why is strawberry split into pieces the model can't see inside?; How does a model learn spelling at all?; Why does letting it write the letters out fix the count?; What else do tokens explain? — page 3: Why Strawberry Hides Its Letters
Chopping splits the word strawberry into familiar pieces, straw and berry, instead of ten separate letters.
Then each chunk becomes a single number. Straw is one number, berry is another. The exact values differ between models, but each chunk is one item.
The model never sees the letters, only number codes for chunks. So it's like counting marbles in two closed boxes without opening them.
So the miscount isn't sloppiness. The letters were never handed over. Any answer has to come from somewhere other than looking, and we'll see where next.
The model doesn't miss the r's in strawberry; it was never shown them, only two sealed chunks, so counting them is a guess, not a look.