1. As many others have mentioned, if this is a public school, it's quite unlikely that this teacher is college educated as a programmer, let alone has ever been a professional developer. I'm sure they're teaching VB simply because that's what they have experience with, probably making them the most experienced programmer on staff at the school.
2. High school bullies are typically quite good at restricting their bullying to times when they're unlikely to be spotted by an authority figure. As a teacher, you try hard to maintain awareness of the entire room as much as possible, but there are always tons of gaps. You might be writing something on the board, helping a student 1-on-1, addressing some other kid's behavior, or doing any of dozens of other tasks.
3. Most teachers try to keep tabs on their students on a personal level, especially when they behavior or attitude noticeably changes, but not all students open up. It takes a lot of effort to maintain an authentic connection. Parents have trouble connecting authentically with their children--imagine doing it with scores of students per semester. And when it comes to bullying, most teenagers downplay to avoid being though of as a snitch. Some are self-conscious to be bailed out even when they haven't "snitched".
4. For many of the author's suggestions, the teacher may be doing these things (recruiting, cross-promoting, etc.), to the extent that they have time. But these are outside the job of teaching. These are things the author could be doing at the school too, but presumably she's too busy. I'm sure the teacher can relate.
Teaching high school was by far the most grueling and emotionally taxing job I've ever had. My work career also includes being a custodian at a health club, a baseball umpire, a senior software engineer, and and a startup founder. None of those jobs is anywhere near as demanding.