1) When a thing is likely to be done better by individuals than by the government. Generally speaking, those personally interested in something are more fit to determine how, or by whom, the business should be conducted.

2) Even when officers of the government may do  better job, it is desirable individuals should do the thing as a means of mental education: strengthening active faculties, exercising judgment, and giving them familiar knowledge towards the thing they have to deal with.

3) Restricting the government’s interference keeps from adding unnecessarily to its power.
When citizens expect the state to do everything for them, they naturally hold the state responsible for every evil that befalls them. When everything is done through the state bureaucracy, then nothing can be done if the bureaucracy doesn’t want it. And the more successful the state is in drawing in, and educating, for itself, the persons with the greatest capacity, the more complete the bondage is for everyone… including the members of the state themselves. 

The absorption of all the principle ability of the country into the governing body is fatal to the mental activity and progressiveness of the body itself.