Really the only thing blocking things like this from existing en mass would be the expense in crafting them.
The concept of the behavior enforcing item can be used widely, and this is a decent version.
In many medieval settings, I don't see this device replacing the headsman's axe or other corporal punishments except for overtly 'enlightened' societies. The rich might get collars, the riff-raff get the axe and the rope.
A rather large armed group slowly walks the road. Unless you get to see what they transport, you could think it is a caravan with expensive goods, or the soldiers escort someone important. But this is a prisoner transport, on the way to mines, criminals on their way for punishment.
The soldiers may be willing to talk, the captain will have a few questions on you and the road, but they will keep distance, and part soon.