Why us?

"Why's everybody always pickin' on me" - lyrics of Charlie Brown by the Coasters
In response to my last post, Dangerous statements for librarians to make, Robin Henry asks a question I am sure many of us have asked over the years:
... why do librarians constantly have to justify their existence, when classroom teachers do not? I have also seen some pretty disengaged teachers in my professional experience, and yet, they are not marginalized as a group, the way librarians are.
What makes us different from classroom teachers or other, seemingly less vulnerable, positions in schools?
Why us? We're important!*
There are two simple reasons as far as I can tell, and we don't like to acknowledge either one of them. First, classroom teachers have primary custodial responsibility for kids. Schools have been given the charge of containing and protecting children and young adults by society. There has to be someone in a school to do this even before anything educational can be undertaken. Unless the librarian is in a fixed schedule that offers teacher prep time, librarians do not help fulfill that obligation.**
Classroom teachers also have responsibility for a mandated*** curriculum. (This is why teachers of electives in high schools are more vulnerable than social studies teachers.) For states that have mandated research skills, "library skills," information/technology literacy skills, it is most often the classroom teacher, not the librarian, who is held accountable (teaching, assessing, remediating, reporting, etc.) for teaching them.
Librarians are support personnel. And support personnel, far more than regular personnel, must have a "customer/consumer service" mindset to survive and thrive: "It's not about us, it's about them." 'Cause if you ain't providing valued service, why are you needed? (Operative word: valued.)
The other comment to the post that struck me was from Judith who wrote:
Yes I've heard similar phrases and yes it frustrates me that our profession is judged by them. But please don't let this be about library bashing as there are some amazing professionals out there.
Judith, bashing wasn't the intent, but maybe a little "tough love" was. And for what it's worth, I suspect I've said some version of many of these dangerous statements myself. I believe we are a profession that can only be reformed from within and that means some honest self-appraisal.
* I DO think good library services are of genuine benefit to every child. But is about what school boards, legislators and administrators think that matters here.
** I think is why not allowing kids into the library for some reason what really rankles many classroom teachers. "Don't we all have a shared responsibilty for supervising our kids? Why do you get to do so when you want to and I don't?"