what makes it so hard

I always tell people that my job is like being a doctor who has a patient come in and say "it hurts" but not being able to say where. When the doctor goes to listen to a heart beat or breathing, she discovers she has no stethoscope. All the nurses are on their lunch break all of the time, and your reference books are all out dated.
The pace of the day is so fast and the stakes are so high and no matter what program you're in, there can never be enough support. Meanwhile, as a teacher you are required to play so many roles: parent, doctor, educator, intellectual, administrator, etc. You fight more battles than those in the classroom, reaching out to parents, fighting outside influences, etc.
I am not going to take this time to discuss the values of various programs, but I will say that so far there are few alternatives to filling need for teachers. For now, these programs get bodies in the room, bodies with a lot of energy and willingness to learn, but also an awareness that it should be better. That feeling is what has made many of my colleagues leave. They know it should be better and they can do better somewhere where they don't have to fight as hard.