Tag wiki has different text for edit access depending on tag wiki page existence. This happens when user does not have right to edit tag wiki page.
When tag wiki page already exists:
To edit this wiki, you must have at least 100 upvotes on non-community-wiki answers in this tag (you currently have 3), and at least 2000 reputation.
When tag wiki page does not exist:
Tag wikis can be edited by users with more than 2000 reputation, provided:
They are in the top 20 answerers for this tag or
They have a total score of 100 or more for this tag
The difference is They are in the top 20 answerers for this tag. Or are the rules actually different for editing an existing page and for creating a new page?
Also, in the latter case, the page does not tell me how many related votes I already have.