Why does it have to be so complicated?  Marijuana is fundamentally a weed. It will grow just fine in a farmers' field. Let farmers grow it and sell it in Loblaws.  There can still be age restrictions (like there is on beer in grocery stores). Plus that scenario would put the black market completely out of business.
The strict regulations the Liberals are working on, with accompanying high retail product cost, will allow the black market to thrive.
Is it conceivable that the people who control the black market in marijuana... which is a big business... are politically well-connected and are influencing the marijuana legislation to keep their market alive.... with prices high on the legal product??