In the author's mind, it's unexpected/amazing that 'for' can iterate over many types. But it's NOT unexpected/amazing that 'iter' can iterate over many types. I have no idea why.

It's not like 'for' is limited to counting in other languages. The grand-daddy in c does something until some condition is false, and that thing can equally be incrementing/decrementing a number or invoking some function. That's what a loop does in any case, it compiles down to a conditional jump (JNE/JE..)

Maybe his reason for astonishment is obscured by over-use of an LLM to 'enhance' the text.