Without jumping to insults, I think at least one of the major reasons the situations you described differ from the one at hand is because of the power differential. Dressing up as a group of people who have been oppressed, marginalised, and disrespected for a very long time (and even today) comes across as essentially…

You're incredibly ignorant.

Yeah, Australia is racist-as-fuck (Sorry Aussies, not all of you are like this, but come on, you still have televised blackface)