In “Out of the Past,” the ninth episode of Nickelodeon’s The Legend of Korra, supporting character/love interest Mako single-mindedly dedicates himself to rescuing Korra from the clutches of big bad Amon. He personally witnessed Amon’s terrible power back in Episode 3 (“The Revelation”);…
It probably has to do with the lack of emotion showing guilt or remorse in Mako’s face for the actions he’s undertaking that are hurting two women who are already sympathetic/empathetic to us and the fact that he’s quick to get upset at other people when they expose his own wrongdoing. With Tahno we can see Amon has broken him and he has earned a level in kindness. There is the promise of redemption for him but with Mako we can’t be so sure because he just seems to be oblivious to his mistakes or doesn’t give a flying fudge about how he is hurting people. If we could actually see him wrestle with what he’s doing the way Zuko did, we could make more of a connection with him. And yes, his wrongful actions do lack the corresponding punishment for them which leads us to become frustrated and fear they will not be punished at all. It makes us disgusted and yes, that is how real life is sometimes but in such scenarios, we regard that person who gets away with hurting others as a jerk and rightly so. We don’t excuse them for the behavior. We rage at the heavens for not making them suffer some sort of consequence for their actions.
This oversimplifies the situation. This isn't a Last Airbender conflict that can be resolved by the end of the episode with heartfelt talk and a group hug. We're dealing with powerful, volatile emotions. We can't reduce them down to right/wrong.
Tahno "earns" nothing from his brush with Amon. Perhaps his experience has humbled him. Good. He has a long way to go before he's redeemed himself.
When you say Mako "gets upset" when confronted with his wrongdoing, I assume you refer to the kitchen conversation in Episode 10 (since Asami never makes her concerns known to him in "Out of the Past"). But let's look at the scene from Mako's perspective. He's just walked out of a super-secret, double classified meeting with Tenzin, in which it was determined that Republic City faces imminent attack by Amon and the Equalists. He has a lot on his mind; his immediate concerns are bigger than his relationship with Asami, and he says as much.
Later, as they rush to rescue Tenzin from the Chi Blockers, Asami informs Mako that she doesn't feel like sitting next to him right now, and maybe he'd like to spend some time with his real girlfriend in the back seat. As the city burns around her.
Is her anger "wrong?" No. He hid something from her. That doesn't make her right: she makes it clear she's more interested in blaming him than working it out, and conspicuously never talks to Korra to get her side of the story.
Asami is not perfect.
Mako is not perfect.
Korra is not perfect.
Bolin is perfect, and that's why he never gets to do anything.
(That was a joke.)
And that's okay, because I understand that I am not perfect. I am capable of making these same mistakes. I have made these same mistakes.
Empathy.