Professors get tenure so that they do not fear for their careers in pursuing their research, judges get such tenure as well so that they do not have to do what is politically popular in following and upholding written laws. High school teachers are not typically engaged in research projects that need tenure protection and in the interests of the community in having great teachers who can be fired if they fail to perform outweighs benefits of tenure for those teachers.
I think that teacher tenure should be eliminated especially at the high school level. I do not think that a teachers should be able to just hold a job without any kind of limit or evaluation of their role. I think that there shouldn't be a tenure in any grade.
Teacher tenure should be eliminated on the high school level and should be different of the college counterpart. Too many high school teachers start to slack off after tenure, and that will only ensure that they cannot get fired anymore. What needs to happen instead is to offer them bonuses when they do a good job, and I really believe that is a better alternative.
Teachers with tenure often learn to abuse their power at the high school level. This may not make sense, but it is the best description. I have often seen teachers who assign as much work as possible so they seem to be "the best teachers" in the school. And the administration always bought into it. The newer teachers - the ones with the modern ideas who can relate to us more - have much less protection. These teachers are also the ones who assign only the necessary schoolwork and administer proper, curriculum relevant exams. It can't be a coincidence that, in general, teachers with less tenure protection tend to be more careful of their jobs. In fact at my old high school, there was an AP biology teacher who could get way with teaching his students only 40% of the course by April, leaving them to cram in the final month before the exam. Tenure is a deterrent to hard, careful work by teachers.
I believe that tenure should be available at all levels including high school, I believe that the standards of getting tenure should be stricter then they are so only the best of the best are able to get it, I do believe tenure gives the teacher a piece of mind at their job and it makes them provide a better educational experience.