Besides as the sibling pointed out the backpack, what do you do when you're driving 80 on the highway and a kid unbuckles? Do you slam on your breaks, cruise t

Besides as the sibling pointed out the backpack, what do you do when you're driving 80 on the highway and a kid unbuckles? Do you slam on your breaks, cruise to the shoulder, and sit in a dangerous place on the highway while having an argument with a 4-year old? If the goal is to keep everybody safe (including the kid), that would be terrible, terrible advice.