Because often there is a large cost: an expensive taxi ride, another to pick up the car the next day, and that's if it's not towed from wherever it was left, ma

Because often there is a large cost: an expensive taxi ride, another to pick up the car the next day, and that's if it's not towed from wherever it was left, maybe you end up late for work the next day and reprimanded/fired because you can't manage it in time. There are incentives if you're borderline. But making punishment harsher (which itself ends up causing more problems beyond the nominal punishment itself) isn't the only way to tweak the incentives. Promote walkable infrastructure so you don't need to drive at all. Establish a government rideshare program to pick drunk people up and take their cars home. But anything that gets seen as helping criminals or the undeserving is untouchable