Well multiple actions in both cases. If you're making a text post, you need to 1) write the text, 2) click submit. Likewise with an image, 1) upload image, 2) click submit.

I suppose the confirmation isn't strictly necessary but for a normal user's use-case, but having a confirmation is a good thing (accidental irrecoverable deletions are bad). But they could definitely have a one-click delete with an Undo button.