Well you did specifically say biology doesn't make it justified. Which I agree.. that's a fallacy. But the only thing that does or doesn't make it justified is your own provincial form of morality. Which as you noted is just one among many subjective standards.

people still own slaves.

Again, that's because you've never lived in a society that focuses on rehabilitation rather than punishment so people who do it once are prone to do it again.

I think that kind of dictatorship would be harmful to the mental health of the people.

Smoking and not wearing a seat belt are your prerogative. Letting you maintain control of what you do with your body even if it's self harm is less harm than taking your freedom which would have a huge negative impact on your mental health.

to be fair you're not figuring in the suffering said policy would cause

Not in the United States.

So our morality is more evolved?

Yeah, where are you lost?

Even then, lets say we have a problem with drunk drivers. Is it more helpful to just kill them all or is it more helpful to provide better resources to prevent drunk driving?

Other than the 'Live Free or Die' state, seat belts are the law in the US. Too many people flying through windshields raises my health care costs and auto insurance rates.

**** those people's 'self harm' instincts.

In context of our history, yes, but we still tend to use ****ty justifications and cultural norms to hide us from uncomfortable truths about our own morality in this country.

No, you're just presenting a false dichotomy to prove a point. My third option is exactly why your point is bull****.