The robbery case is certainly blackmail according to my definition. I agree it sounds strange to call it that way, but I am quite happy to call it "extortion". And I think the distinction between blackmail and extortion in ordinary language (is it that in blackmail the threat must be to reveal information? I'm not sure, not being a native speaker) is slippery and of little theoretical significance.

The other two are not blackmail because the status quo I am talking about is an actual state, vague to define but roughly composed of the reasonable expectations of A before B makes a concrete threat and changes them. It is not a counterfactual "state of nature" in which the public is not scandalized by adulterers and justice does not punish criminals.