So your argument is, California did it badly, but NZ will do it well?
I have a bridge you might be interested in buying BTW :)
California's a terrible example.
It's been legal for recreational use there partially since late 2016, and fully since 2018 via an incoherent mish-mash of overlapping municipal, county and state laws.
Illegal growers in remote and rural areas there still supply - via unlicensed sellers – over 50% of the recreational market by some estimates.
'Best Practise' legalisation in other States and Countries has seen the govt take control of the cannabis industry – via stringent licensing and enforcement - from production right through to wholesale and retail.
Multiple studies have shown that youth – in particular – are very susceptible to glossy, brand specific, peer oriented alcohol marketing, and recent studies show cannabis is no different.
A careful and cautious, staged opening of licensed retail outlets with strong regulatory frameworks needs to be in place. Either complete prohibition on advertising, or allowing minimal branding more along the lines of tobacco sales in NZ versus the free-for-all allowed for alcohol.
Finding the right balance of regulation of cannabis and effective implementation and enforcement of that regulation can result in a net benefit to public health and safety while protecting those who are vulnerable.
California hasn't managed to do that.