Well for goodness sakes no one is saying that human trafficking and ear piercing are the same offenses... my word let's get a grip here.
However, if you want to examine the underlying reasons, justifications, and behaviors which lead up to both, they are similar on a psychological level.
This child is mine to do with what I want regardless of whether I cause them pain.
I am the parent/guardian, it is my decision to make choices with my child's body for my own reasons, even when not medically necessary, and not in the spirit of maintaining their physical or emotional health. (Please, I hope no one is going to tell me ear piercing an infant is emotionally and physically needed or healthy).
I am not concerned with what measure of pain they may feel because in my eyes, it is worth the means-to-an-end. I get the result I want, so I will put aside any feelings or thoughts they may have.
The psychology behind it is the same. There is absolutely no altruistic or non-selfish reason to pierce a child's ears. None. Even with circumcision (which I adamantly oppose) -- at least most people are simply uneducated or ignorant -- they believe it is healthier, more sanitary, cuts infection risk (which we know is not true but ykwim) etc --- very few people simply do it for vanity -- but in ear piercing of an infant or a child who hasn't asked, hasn't had a say in it, and is being caused pain for nothing more than the sake of a parents' vanity and imo, misplaced priorities -- there is absolutely no other reason for it.
I'm sorry, "little Janie looks SO CUTE!!" is not a valid or acceptable reason to hold someone still without their consent as you shoot HOLES through their flesh. Sorry, cute it up all you (collective) like, but that is what is going on.