To have a violent punishment for something like shoplifting or even an armed robbery (in which it's never personal; the guns are to coerce the people into giving what they want) is unfair. Violent punishments for rape, murder and yes, slander, is understandable. But shoplifting? That's not fair at all!
Violently punishing a nonviolent offense is barbaric. For maximum effectiveness, and minimum recidivism, an advanced society should be using punishments that restore balance, make restitution to the victim, and rehabilitate and teach the offender. If a man steals, he should have to pay back what was stolen and make restitution for the pain and inconvenience he has caused. If someone takes, he should have to give. If a woman violates an ordinance that protects the community, she should have to give something to the community. Those who inconvenience others should be inconvenienced themselves as they work to make right what they made wrong. Full restoration should be the ideal goal.
Punishing someone with physical violence regardless of the offense demonstrates laziness, compulsiveness, and a lack of understanding. It exhibits nothing more than a childish desire to inflict quick, easy torment on an offender. Rather than restoring the victim and teaching the offender to understand and regret the pain he has caused, it simply teaches the offender to fear the punisher.
Violently punishing a nonviolent offense is also often tyrannical. Offenses against arbitrary laws and rules made on a whim are victimless, therefore, there is no restitution to be made by the offender. He has simply annoyed a despot, who, in order to strike fear into and exact vengeance on the insolent offender, attacks him with some form of torture or violence. If restitution can not be made for a nonviolent offense, there's a high probability that the violated statute is arbitrary.
If a man refuses to pay taxes and contribute to his society, he will at first be notified, and then told that he has been fined- at some point other men with guns will be sent to his house to do violence upon him if he continues to resist the influence of the state. He committed no violent crime, and yet without the fulfillment of this bottom line- that the laws on which our people have agreed upon must be filled- our society could not function. If this offense was permitted, it would commission a hundred others and no one would pay taxes. Without this tool of civilization we would be reduced to primitive barbarism.
Likewise, an armed robbery does not need to involve the use of violence to be considered armed robbery, only the threat of it. If threat of violence wasn't punishable by violence organizations could amass great armies to threaten civilization.
And furthermore, all non-violent offenses are given punishments, and if the citizen does not comply with the non-violent punishment it must be followed up with violence. Breaking down someones door and then forcing them into a concrete cell is still violence. It is necessary violence, because otherwise there would be no rule of law.
Therefore while violent punishment for nonviolent crime can be considered tyrannical and barbaric in some circumstances when it is unjust, in other cases it is a just necessity.