In almost no category that I've sampled has Walmart ever been the absolute rock-bottom cheapest compared to several places (Big Lots, Dollar General, local grocery chains, Amazon... even Target, believe it or not). People, however, can't go to Amazon to get infant formula, a car battery, ammunition, and a jar of pickles at 1AM and have it in hand immediately.
Walmart used to be about "made in the USA", then it was "always low prices", now it's about "live better". It's Walmart's ubiquity, convenience, and momentum that keeps them dominant (and their ability to loss-leader competitors out of business).
True, there will always be a need for immediacy in shopping. However, on three of the four you listed (Not sure if I want to know why you need ammunition at 1 am...) Amazon carries them, and at a reasonable to very low price. Most of the time I know I'll need something a couple days before. Instead of "I'm out of coffee, better go to the store" it's "I'm running low on coffee, better order some and it will be here in two days". Personally, I find that to be more convenient most of the time.
> Not sure if I want to know why you need ammunition at 1 am...
Zombies. That's the real mistake we're making with shifting all our purchases to Amazon and their just-in-time delivery. There will be nothing to loot when the zombie outbreak happens.
Unless you know where the warehouses are... But surviving the zombie apocalypse in a wal-mart store or a huge mall has much more style then doing in a damp worehouse in the middle of nowhere. That is unless amazon is changing that bit about zombie outbreaks, too!
The whole point of the original article is you'll soon be able to order all of those (except the ammunition) from Amazon in the morning and have them on your doorstep when you get home from work.
Walmart used to be about "made in the USA", then it was "always low prices", now it's about "live better". It's Walmart's ubiquity, convenience, and momentum that keeps them dominant (and their ability to loss-leader competitors out of business).