Hmm, Members were allowed to make polls last time I checked. You have to remember check the appropriate box prior to posting a new thread, and then you need to put in the details before a certain time limit. After that time, only Moderators can edit a poll. I guess what you've seen are the occasions when a Members has forgotten to check the box, or run out of time when filling out the details, and the forum Moderator has edited the thread for them.