Many others, especially in recent years, have been proposed and created by Guest Editors.
The way I run special issues with guest editors is different from what I have heard other journals do because I maintain control over the review and decision process. I have heard that at least some other journals turn that role completely over to the guest editor(s).
What I have the guest editors do is (1) to review papers before they are submitted to filter out those that will clearly not survive the review process or are for other reasons not suited to the special issue, and (2) to recommend potential reviewers to me.
Eventually, each paper will have one reviewer who is a guest editor, plus to other reviewers. All three of these are anonymous to the paper authors. I pay a lot of attention to the reviews of the guest editor. If the guest editor recommends rejection, and the other reviewers are largely in agreement ("rejection" or "major revisions"), then I will reject the paper.
If, however, the other reviewers recommend rejection, but the guest editor does not, then I will contact the guest editor and discuss the issue, before I make the final decision. I will not reject a paper without contacting the guest editor to see if the guest editor agrees.
Full acceptance of a paper, on the other hand, requires acceptance by all three of the anonymous reviewers (or at least those who are left after a couple of rounds of reviews). This is the same as the process for all papers submitted to TG.
In sum, special issue papers are less likely to be rejected than non-special issue papers submitted to TG, but must still meet the same requirements to be accepted as other papers do. Also, reviewers tend to be somewhat more lenient toward special issue papers (though not always), which can gives them some advantage.
So, even though guest editors are not in full control of accepting or rejecting a paper, they have a lot of influence.