There are some crimes, where if a relative or friend were to interrupt the crime, and to see what is truly going on, the absolute lack of empathy from one person, for another and the suffering they are inflicting - thinking about abuse in all its physical forms, Child abuse, Murder, torture - while violence is not condoned in any way in society, if a person caught the abuser in the Act, or shortly thereafter, and took natural reaction to its potential end result, there would be a death, the Victim would still be the victim, dead or alive
There would still be court cases, where all aspects of the victim, the person carrying out the initial crime, and the person carrying out retribution would all be heavily scrutinised
The person carrying out the retribution would almost certainly receive at the least a jail sentence
In the absence of this intervention, and immediate retribution, the Court system takes over control of the event. The Jury and the Judges have limits , with relative impartiality compared to the victims, and those most closely related to the victims, on what they can impose.
Some crimes, where the truth of the matter is absolutely clear, where great harm has been done to another, are deserving of the death penalty being at the very least, possible to impose if the Jury is unanimous in that decision.
The Victims, or those who are left behind, are able to have complete and full closure on the matter.
The Taxpayers (and for each prisoner kept alive who would have potentially have had their lives ended had they been caught by someone able to take action immediately after/during the event - there are 20 people working full time, where ALL of the taxes they earn, and pay to the Government, and all deployed in keeping this person in jail, fed, secured, tTV, education, power, water, phones...)
There is little that is fair in these outcomes
The money saved, can be used to spend more on public information about how to deal with those negative emotions and drivers that are at some level, the reason for such little empathy for a fellow human being