The big difference is the other case the kid was convicted of murder in a jury trial. He got drunk, stole a truck, killed someone, fled the scene, then ran from the cops. The kid apparently was a shit head that had other run ins with the law.
Ethan Couch plead guilty to intoxication manslaughter. People hardly ever get time for manslaughter without prior history, and especially where there is a plea deal and the person is a juvenile. I'm all for hanging the little shit up by his big toes for the rest of his life, but that just isn't how the system works. With him getting probation and violating it the way he did, I bet he is looking at 20 plus years. Momma is looking at some time too.