And also there is a lot of cases where you really don’t need or want static typing. Static typing and type systems are great when they helping you but very bad when you are forced to fight them due to compiler problems or bad modeling.

In the end it is all an engineering problem: which amount of your budget you need to spend on proving programm correctness. Cost/benefit and all of that.

Static typing and unit tests don’t make your codebases great, safe and supportable. Thinking and understanding your usecases, decomplecting problems and some future planning wins.