It's not the retailer side that's the problem, it's the manufacturing side. CostCo is almost certainly not going to get into the appliance market. It's a difficult market that's not very similar to other electronics or other home improvement segments. Not to mention that CostCo's economies of scale with appliance manufacturing would be terrible. They would be limiting their hypothetical appliance manufacturing business to one retailer in one country (albeit a very large one). Not to mention current tariff risks. A "basic" class appliance SKU would be more sensitive to the relatively higher costs for manufacturing in the US. Appliances are manufactured in the US, but the economics would be more negative on a relative basis for a "basic" class appliance brand owned by a retailer.

I am not very knowledgeable about CostCo's in-depth per-segment strategy, but I suspect appliances in particular are more sensitive to margin issues even on the retailer side. Appliances are big, bulky and difficult to deal with (on a relative basis).

Don't get me wrong, I would welcome more competition, but what you're proposing is likely not possible. You would probably need regulation considering the nature of the appliance market.