Okay, what happens if I try to sell you random substances and the authorities dispatch police officers to stop me and I do not comply because I want to exercise my right to trade with you? I can tell you. Violence.

If you disagree with me again, I am going to punch you, but it's not violence because I'm not doing it if you don't do it again ;)

You don't have a right to endanger public health.

So you don't deny that enforcing a ban requires violence, thus a ban is an extreme and violent stance to take and only makes sense if there is evidence that harm can be prevented, which was my initial statement.