Everyone has been treated badly by members of a different group at some point in their life, and responsible adults are expected to get over it and get on with things.

This may be the way now, but it doesn't have to be the way always. Max Hastings, my favourite WW2 historian, says in his All Hell Let Loose:

One of the most important truths about the war, as indeed about all human affairs, is that people can interpret what happens to them only in the context of their own circumstances. The fact that, objectively and statistically, the sufferings of some individuals were less terrible than those of others elsewhere in the world was meaningless to those concerned. It would have seemed monstrous to a British or American soldier facing a mortar barrage, with his comrades dying around him, to be told that Russian casualties were many times greater. It would have been insulting to invite a hungry Frenchman, or even an English housewife weary of the monotony of rations, to consider that in besieged Leningrad starving people were eating each other, while in West Bengal they were selling their daughters. Few people who endured the Luftwaffe’s 1940–41 blitz on London would have been comforted by knowledge that the German and Japanese peoples would later face losses from Allied bombing many times greater, together with unparalleled devastation. It is the duty and privilege of historians to deploy relativism in a fashion that cannot be expected of contemporary participants.

In other words, a boy being bullied at school or a girl shrinking in disgust and fear from a drunken man's cat-call do experience suffering and negative emotion on their own scale of awfulness - and the fact that millions of people in the 3rd world have it much worse "objectively" doesn't take away from the trauma of a "minor" incident in a happier life.

Of course, the objectively worse suffering in the 3rd world should be dealt with as a higher priority. But this doesn't mean that, given a choice of spending a bit of resources and attention on relief from such "minor" evils (at a low enough alternative cost), we should tell their victims: "Stop whining, we don't care."

If we stop aspiring to treat every individual according to our ideals - as sacred, an end in themselves - then there's no Schelling point to stop at; we might as well come to some absurd hedonic utilitarianism, painting smiles on souls, or overwriting people's brains with a simple utility function, or such! Did you, perchance, choose specks on torture vs. specks? If you did, please think and reflect hard before discounting "minor" oppression.

Oppression? No. Calling these sorts of incidents 'oppression' trivializes the suffering of the disenfranchised millions who live in daily fear of beatings, lynching or rape because of their religion or ethnicity, and must try to survive while knowing that others can rob them and destroy their possessions with impunity and they have no legal recourse. You might as well call having to shake hands with a man you don't like 'rape'.

I was going to upvote this until I got to the last sentence which seems both needlessly inflammatory and not accurate. The essential point you've made does however seem to have some validity: There's a scale difference in different types of mistreatment, and using the same word for all of them is something that can easily cause connotative problems.

Everyone has been treated badly by members of a different group at some point in their life, and responsible adults are expected to get over it and get on with things.

Yes, but how common are those actions? For example, as someone who is of Ashkenazic Jewish descent in the US, I occasionally get mistreatment based on my obvious ethnic heritage. But such events are extremely rare- I can literally count the ones I remember on one hand. That's distinct from some other groups- for example if I were a black man living in the US I'd likely have a list of incidents orders of magnitude larger.

I'm not downvoting this comment because I don't want to increase the chance of people being penalized for answering it.

From my point of view, you're punishing Will because he's learning something, but not quite in the way you want him to. He's made himself somewhat vulnerable by asking a question.

Everyone has been treated badly by members of a different group at some point in their life, and responsible adults are expected to get over it and get on with things.

Depends on the venue. In some places, telling the truth about your internal states is valued more highly.

Calling these sorts of incidents 'oppression' trivializes

Look more closely at the context, in particular the description of the experienced internal feeling and the resulting self-suppression of identity. Regarding triviality I refer you to the word "albeit" which prefaces a more than adequate acknowledgement of scope. You may further observe that I explicitly refrained from judging whether the treatment of Will was appropriate or not, much less to what degree it was inappropriate---because getting caught up with how "bad" the people are behaving to the person completely misses the point

You might as well call having to shake hands with a man you don't like 'rape'.

No. I might not. And not just because the scale of the outrage. Primarily because that implies that the man is a "rapist" when we have no indication that it is him who is forcing the other to have the hand shaking (or have sex). If neither the disliked man nor "you" wishes to have sex but for some reason you are coerced to have sex with each other then he is not raping you.