An edit to the answer I posted was not approved by me and still the edit is visible/effective, how?, moderators used their special privilege?
When you post anything on this site, you are giving implicit permission to other users to use or modify your post. Any user can do this, if their edit is approved by another user. Edits by users with 2,000 reputation points do not require approval. At present, there are around 1,000 users who have 2,000 points.
(Your permission was given when you agreed to the site's Terms of Service. The permission is mentioned at the bottom of each page:
(The part that says "user contributions licensed under…" means that your contributions are considered to be licensed under that license, which means that they may be used or modified by other people; full details are here.)
In short, that is how the site works.