I get your frustration, especially as a parent, but as a teacher I really resent the fact that you think we don't care about the quiet, studious children or that we are doing things for an easy life.
Firstly, the quiet studious children are often the ones that are going to respond best to our teaching and therefore likely to do well in exams etc - so we'd be mad to to do something that puts their learning/chances of achievement at risk!
Secondly, we think about these things very carefully, we are forever second guessing ourselves, discussing seating plans with colleagues or revising opinions and trying other solutions. Actually, nearly every aspect of teaching, including seating plans, are under microscopic examination/observation/pressure from our line managers and senior leaders so there is no way that we would get away with doing anything for an easy life or anything that disadvantages pupils.
Thirdly, we are professionals and have degrees and qualifications in education. We know all about disruptive behaviour, we've written essays on children with anxiety and how to help them make progress, we've sat through intensive INSET training on all the latest ideas and solutions which may help make a difference and, on top of all that, we have a lot of experience and know what we're doing.
And, lastly, most of us are pretty nice, conscientious people who care about your child. We did not choose this career because it pays well or because it is easy or because we would like always to have our holidays at the busiest, most expensive times of the year. No, we chose it because we like kids, we care about making a difference to the next generation and we think learning is spectacularly important and changes lives. And the vast majority of us, after a polite phone call, would do whatever you ask of us.