This seems shitty for consumers, but I think it's not new shit - it's just a window into the reality of exploitation we have all been living with our entire lives and it's uncomfortable to confront that giant turd we don't like to think about.
Retailers like maximum profit and they are going to point to supply/demand to justify it. With these digital price tags, they're just equipped to do it more quickly and more often.
At first, I was thinking: What if I grab an item from the shelf and then it's 20% more expensive by the time I get to checkout. Then, I realized they're just going to claim I saw the final price on the checkout summary and should have denied the purchase at that time.
If we legislate anything, it should be the clarity around checkout/returns imo.
It is a requirement of both Android and iOS app stores to have a policy prominently displayed for users.