It is legal if you're in good shape and therefore the risk of that happening is minimal. It is illegal to drive a car under an altered state that makes it more likely to happen. It is a balance between the benefits of permitting something and the likelihood of something bad happens. In normal conditions, the benefits are believed to outweigh the risks, so it is generally permitted to drive a car. But it is not permitted to drive it if you're under the effect of some substance that can alter your perception of reality.

OK, that's fair. So I agree that:

> You can't do whatever you want with your body

is pretty reasonable, but how about we rephrase it as something like:

> You can't do something with your body that significantly increases the risk of harming others

?

Yes, I would agree with this principle, with the caveat that there could be always be corner cases that deserve a special treatment.

Honestly, if cars were only invented in the last few years, it probably wouldn't be legal without extensive training and licensing