As pavel_lishin says, as long as the bully/their family aren't paying, they don't care. If you drive drunk and crash and disable someone, you're not paying their Medicaid all by yourself. If you did, there might be less drunk driving (though given the poor decision making and impulsivity alcohol precipitates, not that much).

Why would they care?

Also, isn't this just a cobra problem waiting to happen?

I mean cities pay tons of money in police violence settlements but it doesn't seem to stop police violence at all

Perhaps there is an opportunity here for the bully’s parents to go after the victim’s parents to dun some money and increase the loot haul.

“Okay Brad, now I want you to sure to target little Billy, because it seems like his parents would be the type of folks to file a claim.”

/s