You have entirely no clue.
"Tenure" in the vast majority of school systems is pretty much just a requirement that due process be followed before you can fire someone. This usually means a few hearing, some appeals, and an actual cause for firing.
Before tenure, teachers could and did get fired for the horrible offenses such as:
1. Not campaigning for the right school board member
2. Being an unmarried woman who went out on a date
3. Being gay
4. Being older and therefore demanding a higher salary than a new, not very good teacher
5. Daring to question or report wrongdoing of an administrator
If you don't think those things will happen again once tenure is gone, you have no clue. You can still fire someone who is not doing their job well. It happens all the time, even in states with tenure.