I'm not saying it is. Just putting it into context. If we want to save the most lives, perhaps we should focus on the political choices which are killing the most.

This is not only about saving lives, it's the ethical point of it. Drone strikes are horrible, death penalty is horrible, both can be talked about.

I can't understand why American society has this need for narrow-focus in ONE specific issue at a time, is there a reason for this cultural approach?

"why American society has this need for narrow-focus in ONE specific issue at a time"

This isn't an American phenomena, it's a human one. EVERYONE can only focus on one issue at a time. It's a delusion that we tell ourselves that we can focus on more than one thing at a time:

https://youarenotsosmart.com/2012/04/24/yanss-podcast-episod...

(That doesn't mean we can't talk about one and then talk about another, which is probably what you meant. But you still have to do one at a time, or make a comparison, you can't just consider all issues simultaneously)

So it can ignore everything else while business goes on as usual...

It is the erroneous belief that every topic, including those concerning human life, can be a relativism.

The corporate controlled media likes divide and conqueror as a propaganda technique, you'll see people copying it a lot.

Why do international megacorporations like it so much? Probably some tangential hangover of union busting.