The laws and rules of states and municipalities are often different, although usually not drastically. Plus each police department has its own policies. There is nothing wrong with that, and in many ways is preferable to "one size fits all" rules.
I agree that this shooting seems very unnecessary and it is odd for one officer to shoot out the other officer's window. But, as in all cases of police shootings, there is often a rush to judgment. We should be learning more soon. As for the body cameras, they work in different ways. But my understanding is that they are not "always on". But are usually activated when the officer exits the car etc. If the woman approached from the side, obviously the dash camera wouldn't have caught anything. But obviously the Minneapolis Police will have to be doing a LOT of review and training perhaps. They had the Philando Castile shooting previously, which personally I found to be completely unjustified. And recently the shooting of the two dogs in the backyard of a home. Plus, if the report is true about the identity of the officer that did the shooting in this case, there will be the added politics of him being the first Somali officer.