My own example of intrusiveness is the Math teacher and TAG teacher asking my daughter what sort of prep work I did with her on math (in preparation for a placement test). It is none of their damn business, and if the elementary teacher did her job it should not even be an issue.
We took our son out of public school and began homeschooling when, during the parent-teacher conference at the beginning of the year (6 weeks into the term), I asked the teacher when we could expect that basic number facts such as addition and subtraction would be taught. Her response (direct quote), "If that is a concern to you, I suggest you and your son work on that stuff at home."
We had him out of there by the following week and never looked back.