How are people punished or rewarded under the king's system of justice in "The Lady, or the Tiger?"

The narrator of Stockton's "The Lady, or the Tiger?" describes the king's semi-barbaric method of administering justice as "perfect" in its fairness. 

When a subject is accused of a crime that arouses enough interest in the king, his subjects are summoned to assemble in the galleries of the amphitheater. The king sits on his throne with his court in an elevated section, and the accused is summoned to the arena of the amphitheater. There, opposite the accused are two doors beside each other, exactly alike in appearance. This person charged with a crime must approach these two doors and open one of them. Either door can be opened.

He was subject to no guidance or influence but that of the aforementioned impartial and incorruptible chance.

Behind one door is a fierce, hungry tiger which will spring on the accused and tear the person to pieces as punishment; professional mourners then appear and the subjects file out with heads bowed in sorrow that one so young has met such a fate. 
Behind the other door there is a lovely maiden, and the accused is married immediately as a reward for his innocence. If the accused is already married this does not matter because the king "allowed no such arrangements to interfere" with his reward for innocence. Then, the happy couple departs, followed by a band of choristers and dancing maidens who blow golden horns, creating a merry tune. People shout happily and children strew flowers in their path.

This is king's method of justice; "its perfect fairness is obvious." For, the accused cannot know which door will hold the tiger or the lady. Certainly, too, the judgments of the king are swift and final.