Dollar General is like a micro walmart and stocks the exact same stuff for more or less the same prices. They are actually great little stores that, around me anyway, service communities that would otherwise have to drive 10+ miles to get what they need most of the time.
Dollar General and Family Dollar both sell things over a dollar.
Yes, everything is $1.
The strategy is predatory: You take a product like name-brand dish soap, divide it up into smaller containers (but not small enough to be obvious!) and presto, your soap is "cheaper" per unit, when in reality, you're charging more per oz. Then you make it as convenient as possible: more locations that Starbucks, nice rounded off prices so customers don't have to do math, and so on. The bottom line is that you end up profiting by over-charging poor people who either don't realize what's happening or have no other viable options.
I'm not sure why this is especially "predatory". It is totally normal for smaller quantities of an item to sell for a higher unit price.
Wheat is trading for $229.00/metric tonne right now. Loaves of bread are selling for about $5.00/kilogram, or $5,000/metric tonne. Is that "predatory"?
No, it does not work like that. They take no-name soap and water it down so a 32oz bottle is $1. The stuff is more stepped-on then frat house cocaine.
They also have smaller, more concentrated bottles. That is what I buy.
Another strategy would be "shrinkflation" (great Planet Money coverage on this: https://www.npr.org/sections/money/2021/07/06/1012409112/bew...). Over time you'd just sell less stuff for the same price point.
But yes, some of the various Dollar stores have left the strict $1 product rule.