Cannabis wasn't banned initially because of any public health crisis (but various health and crime crises were created by banning it). The British studied cannabis use in India in the 1890s and found that it was fairly benign when used in moderation: https://en.wikipedia.org/wiki/Indian_Hemp_Drugs_Commission
Ethanol has been perfectly fine since prohibition ended...
Prohibition in the US was pretty easy to ignore; alcoholic drinks are easy to make, and the government largely didn't take it all that seriously. For all the temperance crusading that got the law passed, it turned out to be unpopular. Did NZ even try it?
What's the definition of "perfectly fine"?
"there hasn't been a significant effort to re-ban it wholesale at a state or federal level"?
At least in the context of the original parent comment ("doing perfectly fine since prohibition")