Get Me Some

I sometimes hear teachers lament students who don't take initiative:

Joe is struggling in my class. But he doesn't ask me for help. If I reach out to him, sure, he will "let" me tutor him. But he is never proactive about getting help.

But are we, the adults, sometimes guilty of exactly the same thing?

I speak to scores of teachers who say:

I haven't gotten much feedback this year. My principal said he was going to be in our classrooms, but just gets so busy with other things. I really want the feedback, but it hasn't worked out.

My puzzle lately has been:

Isn't it fairly easy for a teacher to get feedback by asking for it -- sometimes from administrators, sometimes by peers? And if asking doesn't work, trying a bit of friendly nagging/charm?

Are there really many stories of teachers who make specific, diplomatic, pleasant, persistent requests -- "Can you come to my Period 3 class and give me feedback on X and Y and Z" -- and get turned down cold?

What am I missing here? Why don't teachers who describe themselves as wanting much more feedback just ask for it?