Why can I make instant changes without approval, but I can't approve someone else's changes without further approval?

Question

I have enough reputation that when I edit someone else's question, the change happens immediately (though sometimes it would be nice to disable this privilege).

But if I see a post with a pending edit and approve the change, the change doesn't happen.
Instead there is a message:

It needs more reviews from other users to be completed.

Changes I make all by myself are instantly approved, but changes that are acceptable to two people (myself and the editor) require further approval.

I'm missing the logic behind this policy.

Answer 1

The logic on why there needs to be multiple approvers for someone else's edit is described in this Meta.SE answer to a similar question: Why does approving an edit require more than one vote?:

Multiple approvers are required on Stack Overflow because when only a single person did it, we had a lot of junk edits go by really quickly. Things which contributed little, things which skipped a whole lot of errors, or things that didn't even really revise the post properly. This was bad.

Multiple approvers thus allows some level of check-and-balance, a second pair of eyes can notice errors that were overlooked. It's certainly not a guaranteed success, but since its instantiation there have been fewer reports on Meta Stack Overflow of such problem edits getting approved.

So I think it's because the edit will show up under the editor's name (which has lower rating), not the approver's name. But if you edit yourself, the edit is under your own name, which has sufficiently higher ratings.