It doesn’t matter whether the teacher has a specialty in music or not: they all face the same problems in teaching music to students. Most schools have compulsory arts classes, and music is often one of them. Whether it’s a chorus class, a band class, an orchestra class, or some mix of the three for younger kids, they don’t get a lot of time in the class.
If a child has a serious love for an instrument, it is up to the parent to seek extra learning opportunities for the student. In public education in the United States of America, the focus shifts from rudimentary arts to none at all. There are fewer options for students in middle and high school to study music because the focus is on passing all the standardized tests.