It's obvious when you think about it.

There's a misapprehension about what soldiers are, I think.

People seem to think they are the police.

The military's job really does gel down to "kill people and break stuff".

That they also take prisoners shows our compassion, but it's not "job 1" as it were.

There are lots of contrasts that should make the differences between cops and soldiers obvious.  Not least of which is what happens to a prisoner of war.  They are captured and interred until the war is over.  This interment is open ended and its length is not altered by the rank or behavior of the prisoner.  There are no trials or evidence presented to decide if they should be incarcerated.

Capturing the enemy on the battlefield is not an arrest.  A prisoner of war is not necessarily a criminal.  At the end of the war a POW is returned home without sanction.

People also seem to think that soldiers must always accept a surrender and take prisoners.  This is not required by the rules of war.  The key phrase about prisoners is, "when practicable".  Surrendered troops can be summarily executed if the capturing unit has no means to guard or care for them.  Yes, children, war sucks.  We do have a policy of taking as many prisoners as we can though.

If the enemy thinks that he will be slain if he surrenders, he will feel he has nothing to lose by fighting to the last.  Taking prisoners encourages him to quit once it his situation becomes hopeless; saving lives on both sides.

This stuff is why the laws of war (things like the Hague and Geneva Conventions) specify things like identifiable uniforms for combatants.  So that we know that the surrendering person is a soldier.  Partizans and spies can be executed summarily regardless of "when practicable".

Which brings us to the current situation.  Please show me the official uniform of the people we are fighting.  The clothing and insignia that distinguishes them from the local citizenry.

Anyone?

Combatants out of uniform are non-entities to the laws of war.  Since we can kill them out of hand, anything less is showing how compassionate we are.  Harsh things are allowed to be done to partizans and spies.  This is entirely to encourage the fighters of both sides to put on uniforms!

When they start putting on uniforms I will start caring in the slightest about waterboarding.

When they start treating our troops in accordance with the rules of war, I will care about how they think about waterboarding.

Until then, however...