Except that the odds were very obviously more stacked against Zuko. Ozai didn't expect him to actually accomplish capturing the Avatar, whereas he did expect Azula to succeed in capturing Iroh, and she actually does. Zuko is sent out after being banished, burned, and humiliated and told he has to "regain his honor," whereas Azula is given every resource and sent out proud to accomplish the task Ozai wanted her to complete.
Iroh is a capable fighter but he's also in exile with Zuko and considered disgraced and when Azula comes after him, he's lost most of his resources while she is the one with the army, and she nearly traps him and Zuko the first time they fight and they literally have to fight their way out. The next time they meet, she nearly kills Iroh. Iroh and Zuko are then forced to go into hiding in Ba Sing Se to avoid her, and she confronts them there and does capture Iroh.
Ozai sending Zuko on an impossible task with no hope of completing it is not really comparable at all.
Also, the main reason Iroh gave Azula the trouble he did is because she constantly underestimates him, but when it comes to raw resources and power she definitely has the advantage. Azula also uses Iroh's love for and need to protect Zuko against him multiple times and that's also the reason she's able to capture him.
Azula is not the victim of big bad Iroh, lol, and this is not comparable to Ozai deliberately sending Zuko out on an impossible task as a punishment.
Azula also has the freedom to accomplish Ozai's task any way she wants with the knowledge that she will be welcomed back as a hero, as shown by her bringing Zuko back as an ally instead of a prisoner as Ozai ordered, whereas Zuko is afraid of not following Ozai's orders to the letter, because he knows that Ozai didn't expect him to succeed.
Not only is this post belittling Ozai's abuse of Zuko by trying to make it seem like Azula being sent out with Ozai's blessing, resources, and expectation of succeeding is the same thing as Zuko being sent out as a punishment, wounded, humiliated, and expected to fail; it also tries to make it seem like Azula attacking Iroh was somehow hurting her, when she hurts Iroh repeatedly. Iroh's age or his capability as a general matter less because not only does he not have Azula's resources, he also does not have Azula's ruthlessness and is in a position where he is trying to protect Zuko and is fighting from a defensive position, whereas she is the aggressor.