It's partially the teacher, but it's mostly that thing we all hear about all the time about a "safe, welcoming learning environment" that makes kids WANT to try in your class.
We have a lot to overcome - and Title 1, rural poverty, and inner city folks have a LOT more to overcome than people think. It CAN be done, but you have to understand where the kids are.
To be honest, this reason is exactly why so many suburban top-flight program kids from top music schools don't want to work in inner cities or in rural areas. They don't know how to, to borrow from Eric Cartman, "reeech theeeese keeeds."