A lot of teachers have a sort of mental "detailed lesson plan". As in, in any lesson I give, I can verbally list all of the necessary information for a lesson plan. Why should I necessarily have to write it down? If it really does help my teaching process (which in my case it does, and I do make lesson plans) then I should make one. But to say it is "part of the job" is silly.

I think there is a big difference here in the term "lesson plan". For teachers, like myself, just out of teaching school, a "Lesson Plan" is a huge, laborious undertaking, requiring a teacher to not only plan a lesson but plan for any problems students may have with the material, plan alternate ways to present material (for students with different "learning styles"), and plan down to the minutest piece of "assessment" (including "discussion" as assessment). For more veteran teachers, a "lesson plan" consists of what is being taught that day, what's being assigned, etc. So the two are very different. When an administrator asks for a "detailed lesson plan", he is typically asking for the second kind. The administrator just wants to make sure that something is going on in the classroom, and to know what the kids are doing that day. When a teacher's lesson plan consists of the topic, i.e. "World War I" or "fractions", that gives the admin. very little information on what to expect.