I was able to reproduce this problem. Basically the admin menu link is the same link as the page list link, but if the user is some kind of admin it points to the admin menu page. The problem is that the admin menu page is not currently showing the link for page tree unless the user is admin, content admin, or site editor.
I will fix this for the next release by adding a check for any create child page permissions and if the user has any we will show the link for page tree. There is a similar check on page tree already and the page actually does work correctly, its just that the link isn't shown on the admin menu as it should be.