But if you take a look at the movie very carefully, you’ll understand that Joffrey wasn’t “cruel.” he was just Someone who actually understands power. He was the only one in Westeros who refused to play the soft, honorable game that gets entire houses wiped out.
Ned’s “justice” almost handed the throne to Stannis. Sansa’s northern pride was a living rebellion. The street trash and gossiping whores? They learned the only lesson that matters: the king’s peace is absolute.
Fear is cheaper than loyalty and twice as reliable. The Purple Wedding wasn’t justice,it was the weak and the sentimental murdering the one person willing to keep the realm from dissolving into anarchy.