I want to write a complaint letter about my teacher?

No, you have no grounds, and you shouldn't be offended. She was just offering an ogy. She could have just as easily said, "It's like the traffic laws- you just have to obey them whether you agree with them or not." She wasn't saying that she agreed with them- just that sometimes in life you are given arbitrary guidelines, and you have to follow them. When you work for a company, they will have ways of doing things, formats for writing reports and memos, forms to file, etc., and unless there's an ethical problem, you just do it that way. You can't argue with everything- save your energy for the big fights.