While true, that is not really the issue. The issue is which lexical scope the loop iterator is defined in. In python, it is apparently like this:

    i = 0
    increment i
    <do loop body with i>

It could have been:

    i = 0
    increment 1
      create new environment
      bind i here
      <do loop body>

In the second case, each loop body would have its own "i". In the first case, they all share the same "i".