Pues claro-but the two kids he ignored appear to be lucky he wasn’t around-caring and intelligent parents don’t buy weapons for their kids who are having obvious mental health issues...
That's true in hindsight, but what we don't know is how aware the parents were of their son's mental health status. It isn't easy to figure out the mental health status of people and when they are likely to be a danger to others. In this case the school teachers, counselor, and other staffers involved had the most recent data about the kid but failed to realize he was a danger to others. And they are trained to detect problems.
In many other instances of mass shootings the perpetrator is under the care of physicians who also failed to detect the risk that their patient was to others.
Saying that the parents should have known, but the trained professionals aren't held to the same standard is not logical. The professionals involved with evaluating Darrel Brooks knew he was mentally ill, and had tried to run over someone, but they didn't send him in for a mandatory mental illness evaluation. And then he drove his mother's car through a parade.