Suppose the president of America decides to kill his critics. The president needs to gather data on many people so the president can decide who is a critic and who is not a critic. The president needs to decide who to kill next. The president needs to travel to the location of the critic. Also the president needs to eat and sleep, and probably wants to take vacations too.
All these things take time. Killing critics is a slow process. I think the president could kill about two people a day. Meanwhile more than two new critics will probably appear every day because people will be outraged that the president is killing his critics. If the president tries to kill his critics, the president will fail to reduce the number of his critics.
If the president tries to kill his critics, only small number of people will die, and the president will accomplish very little.
There are many things which a president could do which are worse than killing his critics.
Suppose that instead of killing his critics, the president enacts bad laws or invades foreign nations. This could result in the deaths of millions of innocent people.
In reality, oppressive government leaders do not personally kill their critics. Oppressive government leaders employ a vast army of thugs and goons, and order the vast army of thugs and goons to kill the leaders' critics.
The world is full of people who want to be oppressive dictators. The vast majority of these would-be dictators are harmless because they do not have a vast army of goons and thugs willing to obey their orders.
I do not seriously think that government leaders should kill their critics. I was trying to show that a government policy without a vast army of goons and thugs to enforce the policy will probably be ineffective.
Often people who support various government policies do not consider the consequences of the vast army of goons and thugs needed to enforce the policy.
If people will voluntarily obey a law, then the law will be easy to enforce. But if people do not want to do whatever the law forbids them to do, then they will not do it even without the law. The law is unneccessary.
If people want to do something, and it is illegal, then people will try to do it anyway.
Once I was talking to an environmentalist. This environmentalist was sorting his garbage for recycling. He showed me a copy of the local government's rules for sorting recyclables. While he sorted, while I watched and read the rules, he passionately lectured me about how important it was to sort recyclables, and for the government to vigorously prosecute anyone who failed to sort recyclables properly. Then I pointed out to him that what he was actually doing was illegal according to the rules I was reading. (He had recently moved and I think he was following the rules of the previous local government instead of the rules of the current local government.) He had denounced those bad people who fail to sort recyclables properly, and now he was revealed to be one of those bad people who fail to sort recyclables properly. He was stunned into silence for a few minutes. Finally he declared that the local government was wrong and he was right, and he was going to keep sorting recyclables his way.
The moral of the story is that people are often committed to acting in a certain way, and often ignore laws which require them to act differently. If the government wants to change peoples' behavior, the government must resort to extreme measures.
And if the government uses extreme measures to change peoples' behavior, the extreme measures may do more harm than the original bad behavior. The government cannot enforce unpopular laws without violating peoples' civil rights.
There are the budgetted costs of enforcing laws: the salaries of policemen, prosecutors, judges, and prison guards; also the cost of constructing police stations, courthouses, and prisons. This requires tax increases or reductions in other government spending.
But there are also nonmonetary costs of enforcing laws. Alienation is caused by overregulation.
Drug prohibition cannot be enforced without extreme measures. When abortion and alcohol were prohibited in America, extreme measures were needed to enforce the laws. America cannot prohibit immigration from Mexico without extreme measures.