"Walmart is the closest thing to "discount, no-frills" in the US, however it's 100% a facade. Their prices are realistically no better than chain grocery stores like Kroger, yet they do a very good job convincing poorer people that they are."
I don't have a Kroger nearby, but WM is far cheaper than any other grocery chain in my area. I go to WM for all nonperishable items and then a more expensive store for fruits/veggies/meats.
They spent a lot of money and energy trying to roll out in store pickup, 2 day pickup, and online grocery shopping, which I have been reasonably pleased with, but I think this is slowly becoming a death sentence for them. The one thing they're missing is the brand.
ALDI doesn't have as much dominance yet. Trader Joes has a bit more, and is all around a great store and reasonably priced compared to Whole Foods.