Why can't a king take a pawn or other piece if that piece cannot legally move?

You and I know those would be dank ass scenarios my sir

Because chess players are lazy and they dont want to make it more complicated.

Think of it as a duel. Your K would die on f3 before you could get off your otherwise fatal shot, Rxh2.

Think of it like this: if the king is captured, the game stops-right there-no more moves are made. Once the first king is captured, nothing more will happen and the player with a king remaining wins. However, we don't actually capture kings in chess, so all this was hypothetical

I guess I need to repost because people are trying to re-explain my highly detailed and vivid explanation

.honorable mention: White K on h2 as "noble white king"

It is a game of non-realtime tempo and white starts out 1 tempo ahead of black. 

PG explanation:  Since the black king has been CAPTURED, the war is immediately over and the royal leader then surrenders his kingdom, his army and all of his assets to the conquering enemy side.  The black rook that was preparing to capture the white king is now recruited as an enlisted member of team white. 

A colorful medieval wartime scenario:  (Rated PG-13)

       In a large open field dividing two kingdoms, an eerie silence has settled in, but in his head still rings the sounds of agonized screams and metal slicing flesh.  His royal garments have been stained by at least 9 different shades of red.  Intoxicated by a mixed cocktail of emotions, he nears the conclusion of a violent and arduous struggle.  The fatigued yet determined black monarch, Kevin, marches deeper into enemy territory at a rigid pace. With death in every direction, he is tormented by the perturbed energy of anxious souls that have been abruptly ripped from their mortal chambers. In his head, a playlist of visions from each of his men's final moments are stuck on a shuffled replay.  The dying faces haunting his memory are following seemingly scripted emotions: surprise and shock, followed by a chilling fear, and then finally displaying a hint of somber acceptance as their fleeting spirit renders them limp.   He carries on, there is no turning back.  He is on an autopilot mission towards his unfinished destiny.   Stepping over scattered body parts and through puddles of blood, the stubborn leader draws his sword as he boldly approaches what is left of his adversaries.  He gives the signal to his sole surviving warrior, a chariot marksman named Rory, to prepare for a final engagement. 

       Geoffry, 19, and Finkledern, 17, were just amateur bodyguards, fresh out of the academy.  Before the sun rose on that day they were no more than timid virgins of combat, but the events that took place on that battlefield had forged them into something else, their old identities left on the ground, as deceased as their fallen comrades.  Broken down and rebuilt they were now essential cogs in the nation's war effort. The only departure from that battlefield they would accept was an entire transformation of either body or spirit.

         As King Kevin approached, the two stone-faced bodyguards stood their ground, loyal to their duties.  King Kevin and the seemingly-confident guard met gazes.   As the bloodthirsty dauntless eyes of the tenacious ruler penetrated the young warrior's soul, Finkledern felt his mortality for a brief moment before the  aberrant enemy became a blur in his peripheral.  Finkledern knew that he was now completely powerless to defend himself from this angle, and he would have to rely on the protection-chain system that they learned at the academy and trust in King Kevin's fear of his own mortality. 
Finkledern could  hear the crunch of King Kevin's armored boots approaching closer and closer, slower and slower.  "Did the footstep stop?"  Why did they stop??"  "Was Geoffry still defending me??"  Finkledern knew something wasn't right.  Finkledern's heartrate began to skyrocket, all of his suppressed emotions were now flooding back in.  He wasn't supposed to be afraid, he knew from his training that if he followed the rulebook, and kept his post, he should be safe from the enemy king, but he was paralyzed by a devastating fear.  He could feel what was coming yet still he did not budge. King Kevin poised himself to strike, and Finkeldern knew it wasn't a bluff.  This was his calling, his duty, and his final chapter.  Accepting of his fate, Finkledern began to relax, time slowed down nearly to a halt, and in this lasting moment of silence he had peace.  He knew he would live on as a martyr, a legend. He inhaled a chest full of crisp air, closed his eyes, and a cracked a smile as he slowly breathed out.
        In an instant, a crushingly tight pinch yanked Finkledern's neck.  He opened his eyes and clenched his hands over his freshly-permeated carotid artery.  He fought against his instincts to panic, but he couldn't breathe.   Kevin withdrew his sword and stood there watching his hapless victim.  Finkledern felt like he was drowning and being choked at the same time, but it wasn't as painful as he thought it would be.  His body violently attempted to cough as blood filled his lungs.   He collapsed to his knees with his hands still firmly on his neck, turning towards King Kevin, blood spraying out with every heart beat.  King Kevin and Finkledern shared this one last moment locking eyes.  Finkledern then managed a small smile as he saw Geoffry's pike skewering King Kevin's head from behind like a shish kebab 

      Fearless King Kevin died with no regrets.  He never had the chance to realize his own mistake, because his memory, and his mechanics to receive and process data had been rapidly reorganized in a less-than-functional manner. 
King Kevin made the fatal assumption that the bodyguard Geoffry was pinned to his duties of protecting his own king from the threat of Rory.  Unbeknownst to King Kevin, when Rory saw simultaneously an open shot on the white king AND his own fallen leader, he thought about his wife and kids at home, and the fact that King Kevin was a d**k to him anyway, and so he choose to surrender and join the other side.
THE END.

did you even read the tale of Finkledern's great sacrifice?  Apparently, you have no appreciation for exuberant storytelling or explicit graphic violence.  And you likely didn't read anybody else's comments either because you have failed to improve upon anybody else's words.

No need to shout.

I'm wondering if perhaps I was a little ambitious with the question, I'm happy this discussion took place and thank you for sharing how to post a PGN. I'm a retired engineer, I am not as sharp as I used to be and not nearly as obsessive. I'm happily retired and chess helps me with an ongoing problem with my memory - it absolutely works. 

I agree that allowing the move would be a violation - but - I still think it is a strange thing. I'm not disputing any expert here, but while I agree in general, I still maintain reservations. That's just me being me.

Thanks to everyone :-)

Cheers

FX

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