What's the issue with public grocery stores? We shouldn't be forced to purchase groceries from one of three megacorps in a trenchcoat.
That they aren't necessary, won't produce a material benefit and will cost billions to set up?
The solution to the oversized conglomerates is to break them up.
Split Empire into 4 (Sobeys, Farm Boy, Longos and Freshco) with zero overlap, different ownership, different executives, different warehouses)
Likewise, split Metro into Metro, Adonis and Food Basics and spin off their pharmacy division.
While Loblaw should be split into Loblaw, (and like), Fortinos, T&T, No Frills and they should have to separate from Shoppers as well.
But that doesn't require a public supermarket system. Just breaking up oligopolies.
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In truth, Canada's grocery system produces some of the cheapest grocery world wide and cheaper now, inflation adjusted than it was 30 years ago. With some notable exceptions.
We're too high priced in dairy (supply management reform is the solution)
We're too high priced in meat, that's supply management in part, but its more a matter of the country having only 3 large slaughterhouses for beef that dominate the market. The facility in Brookside, AB, needs to be downsized by 2/3 and gain 3 competitors in Western Canada.
Finally, we're overpriced for good bread. That's a function of supermarkets have done away with scratch bakery and relying on par-baked crap from second-rate mass bakeries.
Addressing these issues will make grocery more affordable.
Though addressing wage growth and more generous social assistance will do even more.