As I've worked most of my life in schools, and am married to a teacher I realize I have a bias, but some teachers do try their best to help every possible student.

I can't count the evenings we've discussed certain cases and how to approach them.

We've been lucky in that we've mostly had the same students, as I worked with them as they were younger and when they switched up my wife got them.

We did work in special ed. though, focusing mostly on autism, so we've seen a lot of bad situations throughout the years, but I wouldn't go blaming only teachers for that. There are also administrators, headmasters, outside influences and last but not least the parents that all play a role in every students education.

Then again this isn't the US and I know how things look there in the educational sector, so your mileage may vary.