"Or is there an "acceptable" level of risk based on experience (e.g the chances of being struck by lightning) AND the need to get the job done??"
Sadly, since the abolition of Crown Immunity then ambulance chasing lawyers combined with the modern vengeance culture will encourage claims against an individual. To protect themselves, the seniors of any company introduce "Health and Safety" regulations which are, in reality, anti litigation measures designed to protect said managers. If anything happens then someone somewhere must have broken the rules - preferably someone quite junior, who will carry the can and face the consequences. Under such conditions then higher management will NOT accept any risk to either their pensions or their freedom.