Forcing a kid into physical labor over something as petty as a single can of soda is a blatant power trip. If he's getting this upset over having to do it, then you're stripping away any sense of safety and control he could glean from school after having such a terrible home life.
He's not going to think of it as "I did something wrong and was punished for it," because the punishment is so outrageously severe compared to the crime, even as a repeat offender. He's in a bad place, and when you're in a bad place and are humiliated and shamed simply because the people in power say so, you wind up hating yourself and the people who did it to you.
They obviously have no idea how to handle kids with real problems, and are relying on simply shoving rules and enforcement down their throat. If a kid doesn't respond to punishment, making them more and more severe is just going to keep hammering at the person pointlessly until they snap.
He's not going to think of it as "I did something wrong and was punished for it," because the punishment is so outrageously severe compared to the crime, even as a repeat offender. He's in a bad place, and when you're in a bad place and are humiliated and shamed simply because the people in power say so, you wind up hating yourself and the people who did it to you.
They obviously have no idea how to handle kids with real problems, and are relying on simply shoving rules and enforcement down their throat. If a kid doesn't respond to punishment, making them more and more severe is just going to keep hammering at the person pointlessly until they snap.