It wasn't always that way. When I got into guns 10 years ago Canadian Tire was the cheapest place to get 303brit and Walmart was the cheapest place to get 270/308/30-06 - at least the cheapest places around where I lived.Walmart and Cdn Tire don't care. Not their primary SKU driving sales. Any site sponsor here sells for way lower.
I'm happy to support real gun stores, but it was nice to be able to pop into Walmart and grab a box or two for the range rather than drive 30+ minutes each way to Wanstalls. Now Walmart near me doesn't even sell ammo and Wanstalls is gone... =(