Quite a lot of Amos's examples do fall within the "purist" definition. The rest illustrate what I was complaining about.

Tragic irony is basically about the observer seing the contrast between what someone thinks they are doing and what they are actually doing, and with Oedipus the observer literally means the people watching the play. Taking "the Gods" as being the observers I suppose it's a logical enough extention of that to use it even in a context where there are no human observers.

A lot of Amos's examples do actually fall within the purist definition. Where they don't I think that it is still worth resisting the extension of the term to mean anything that is sligtly odd or unexpected. Or where there is a more accurate word, such as paradoxical in this case: "the difference between how you might expect something to be and how it actually is, for example when the slaves in The Two Generals like the brother who believes in slavery more than the one who would set them free"