I avoid Randalls because of their price gouging.
I question if "max pricing" could ever be implemented. There is typically a posted or stickered price on groceries. Walk up customers are still going to want to know how much something costs and they may not buy much at the "max price". Selling merchandise to someone for higher than the posted price can cause problems.
There have already been lawsuits because the register price doesn't match a posted price (the registers don't always have the correct data and the shelves aren't always correct). To bill the customer this way is considered a deceptive trade practice.