These merchants put themselves into these "Lets optimize our profits" scenarios with self checkout, not providing free bags, check out using a phone app then whine about the poor results of their bad decisions. Self Checkout + forcing customers to pay for or provide bags to carry their purchase = Increased Probability for Theft. It doesn't take a rocket scientist to predict that outcome.

At a minimum, these stores should be giving away free bags at checkout as that would at least make it much easier to identify potential thefts. That and the bag itself is an advertising marketing device with the store logo on it. They could at least write off the bags as a marketing expense.

Open up the human staffed checkout lines and give away free bags. Product loss by casual Theft would plummet. Or double down on your poor business model and add Rent-A-Cops to harass your customers.