So you're saying the grocery store doesn't trust her with the cashier and the money?

And I don't know about Canada, but at least with the grocery stores in the U.S., you only earn minimum wage if you're non union or working at a small mom and pop store. The bigger ones, (I'm including specialty stores like Trader Joes) start above minimum wage. It's still one of the few jobs where you can get by without a high school education and still make some money. Mind you, it's still not a lot.
Also, Target, Walmart, etc. aren't grocery stores despite selling perishable foods. Those are a different business model, I think.