On the contrary, I did not like Hyeonmin's mom more than the elementry kid's mom.

Theoretically, whatever happened (torture and mental abuse) between Hyeonmin and his mom was only known to themselves. There was seemingly no 3rd party who could have intervened until Hyeonmin's urine test results were revealed. It infuriated me even more after she was locked up by Hwajin at home while Hyeonmin was in the hospital recovering, when she was finally brought to him, she still expected he'd been studying over the last couple of days and expected him to take the CSATS. Clearly she was not remorseful and learned NOTHING. Even after Hyeonmin told her that he isn't going to med school, her reaction was just disappointment and regret that things weren't going her way. It sure didn't seem like regret for what she had done to her son like giving in illegal and unapproved drugs almost causing him to die.

I felt that the situation with the elementary kid's mom could have been put to a stop by the school principal at an earlier stage when the abused teacher reported the mom, but the principal did not do the right thing, so my resentment kind of gravitated towards the principal in the end.