Believe me I know that for sure. Things sure don't turn out for me hardly ever the way I want them to. I'd be rich if I had a penny for all the times things haven't gone my way. Heck, that could be a new way of paying off the debt. :)
That already happens here to a good degree. But again, there are subjective things that can be considered too.
If someone has it out for the teacher--parent, principal, or whomever, even a good teacher could get fired. A VERY good teacher here who'd won awards for her teaching and training student teachers got a principal who for some reason just didn't like her and failed her on her observations. She was given "one last chance" by the principal and "passed" with flying colors with the principal saying "Oh look you much I improved you." She subsequently assigned the teacher to teach sixth grade when she had done WONDERFUL work teachng third grade. If we do allow complete jeopardy involving the good teachers, we lessen the quality of the teaching in the community and school. I don't have the complete answer now (except for some things like frequent monitoring and parental input), but am just bringing up some points to consider. You're right, sometimes it isn't fair. Sometimes I think that there could be a different way to go about things sometimes.
My own wife got layed off due to outsourcing (of computer programming), and the greed and incompetence of the managers in her company. It is now a shell of what it once was. The president wondered why no one would talk to him like they used to.