It's kind of a paradox. I can see what you're saying, but at the same time, I don't expect e.g. a retailer to be transparent with me about their supplier costs, and phrase their prices as "$2 unit wholesale cost, $0.50 retail storage fee."
The difference is that to get that $2/unit wholesale cost I need to buy 10k units and to get the regular price from the thing on Instacart I just need to go to the store. The latter feels far more achievable.