The IDF has some accountability for criminal behavior. If you search you will find plenty of examples were soldiers were held criminally responsible for their actions. It's true that the default (and maybe the correct default) is to shield soldiers from actions taken during the course of war. This is not unique to the IDF, it's true for all western armies. Try and find me if the US pilot that bombed a hospital in Kandahar, or the US security contractors that mowed down people in the Baghdad market, were ever held criminally responsible.

And just to be clear, my position is that if there was a criminal act here the IDF should absolutely prosecute. To my understanding this is still not settled for this case, i.e. there has not been a decision to not prosecute. But we shouldn't kid ourselves that this is somehow different.