This made me think that it should be the opposite. I thought I remembered az yashir that some mitzriyim sunk like אבן. I thought it was the reshaim but it's the opposite. I forgot. So it seems like you're right.
That leaves me with the question why is it that way. By yidden you get a kappara from tzar. So why dont the not so bad goyim get that benefit?
Something is different. I don't know what. Maybe misa is the only kappara for goyim so suffering is an added punishment. But that leaves a different question why is there suffering by non Jewish children that didn't have time to do any aveiros.
There seem to be many aspects to suffering.
Brachos 5a&b discusses an idea that hashem gives yesurin so we should be מפשפש במעשם, so standard yesurin come so you should realize something needs to be done similar to nerves feeling pain which tell your body that something is wrong, but if you have nothing to fix then it's a sign that these yesurin are of another category that some righteous people whom don't have any sin receive, just to increase their reward in the next world. This suffering is literally for the sake of suffering, and so if the person is מקבל באהבה, it'll be worthwhile, and if not then there's no point which is why in the Gemara they tell each other חביבין עליך יסורין? and when he answers no, he gives him his hand and heals him, cuz if one isn't being mekabel the yesurin shel ahava then there's no point too it.
However in Avoda Zara 4a the Gemara seems to discuss another aspect to yesurin, that hashem gives ONLY Jews, in order to minimize their punishment in olam haba, רשי says ד"ה נפרע ממנו מעט מעט, כן ישראל נפרע מהן הקב"ה את כל עוונותיהן בעו"הז כדי שיזכו ליום הדין ועכו"ם אינו נפרע מהן כלל כדי לטרדן מן העוה"ב
So being that nobody denies that non Jews have suffering as well, clearly we are discussing a special additional suffering that hashems giving Jews on top of what regular ppl would be getting just in order to deduct from sins, but even without this special deduction we would still be prone to regular suffering that the whole world has which goes under the classic שכר ועונש, and הנהגת היחוד which goyim fall under as well.
So to recap I think there's 4 categories.
A) Yesurim that tell you you're doing something wrong and if you get the message they go away.(Not sure if this is exclusive to Jews or not)
B) Yesurim Shel Ahava: Come with No sin just for the sake of giving Special Tzadikim extra reward for accepting the pain. (Only tzadikim)
C) Yesurim to deduct a person's aveiros so he gets less Gehenom. (Only Jews)
D) Yesurim that everyone is susceptible too as part of the way the world works and part of שכר ועונש/הנהגת המשפט and הנהגת הייחוד (where hashem is orchestrating everything to bring about the ultimate תיקון, of וכל הרשעה כולה כעשן תכלה)
which we don't have an understanding of as
@imayid2 mentioned already.
P. S. As far as what you mentioned in regards to מצריים, receiving diff levels of punishment, which at first glance seems to contradict Category C, perhaps this isnt bgeder yesurin, as this is already the actual עונש, and based on how wicked they were, their death was accordingly painful, but both of them received the full punishment afterwards in the next world.
Throughout נביאים, hashem constantly warns the nations about their impending downfall and diff painfall punishments they will get in this world מידה כנגד מידה, but that's always when hashem is taking his revenge and they are receiving their onesh already.
But in regards to everyday suffering in Africa etc, that would be Category D.
