> We investigate them, and maybe issue new regulations, not to punish mistakes,

This is not quite accurate. In the US for example, the NTSB investigates the causes of an incident, and the FAA carries out any subsequent enforcement action. Whereas the NTSB may rule the cause as pilot error due to negligence for example, the FAA may revoke the pilot's license and/or prosecute them in a civil case to the tune of a hundred thousand dollars and/or refer them to the Department of Justice for criminal prosecution.