You both have hit upon a secondary problem. When it comes to firing an incompetent teacher, it is not a level playing field. State laws have somewhat stacked the deck in favor of the employee.
No good teacher wants to work next to an incompetent teacher. I have taught for many years, and I sure don't. But this is not a tenure problem. It just isn't.
It’s a problem in any state that has teacher tenure. Teachers unions should be abolished.