As another commenter explained, the need for permission is there to prevent harm before it can occur, rather than punishing it after it occurs, because the harm can be of the sort which cannot be undone.
If I want to build and sell houses, I should be able to do it, but it shouldn't take going to 10 government offices, filling out 50 forms and waiting a year for someone to give me a permit. And then, once I have built it, it shouldn't take another year for someone to check I did it correctly.