Government and laws don't exist to give people trouble. Rather, they exist to keep people from having trouble.
A criminal might be able to escape the authorities, but if he gets out of the legal system, what is left for him is vengeance. It's the thing that makes wars between countries when people don't have a good judge to control them.
The point is, the choice for the criminal is peaceful judgment or vigilante judgment. Vigilante judgment is usually emotional rather than logical, and the results can be far more in correct.
