I'm bewildered by Amazon here. I would assume every change require code review by another enigneer already, as is standard practice in the industry I work in (i

I'm bewildered by Amazon here. I would assume every change require code review by another enigneer already, as is standard practice in the industry I work in (industrial equipment). Is the change just that it has to be a senior engineer specifically, rather than any engineer? Or did Amazon really not have mandatory code review before?