First, a business owner does not have the freedom to choose how dangerous a workplace he wants
see
http://www.osha.gov
for example: I bet you're glad that a restaurant owner can't decide he wants to save money by not providing soap for his employees to wash their hands after using the bathroom
Moving to the topic, when you impose the risks on the employees, by say having a smoking environment, and say that it's up to the employees to decide whether they want to risk it for the paycheck, it's a coercive situation for the employee, who might be forced to take the job despite the health risks. Furthermore, recent studies have shown significant reductions in cases of health deterioration after smoking bans were implemented. A quick google search will show you a 17% reduction in hospital admissions for heat attacks a year after the bans were implemented, i recall another article where the numbers were up more around 25 -30% reductions. There's no denying that those subjected to the smoke environment are experiencing improved health.
Second, this goes back to an earlier post where you say it's not the governments job to tell you how to be safe, however, it is the governments job to employ an ambulance crew to take care of you, if you do have an accident. If you're going to be putting your self at greater risk for trauma, why do you want the doctors to have to use all the extra resources to keep you alive, when it's just easier to wear a seat belt.
This point isnt' hitting on a single payer health system, but it is leaning towards the fact that the government has made quite an investment in, a. providing the network of roads and transportation standards to allow for you to have the freedom of driving a car, as well as providing the resources that first respond, should something go wrong.