This is hilariously first-order-effects thinking...
If any store used dynamic pricing to expand their margins, the others would just do the same and compete away those margins once again, with the marginal gain being handed back to consumers.
Dynamic pricing on personal data is bad I think, but temporal dynamic pricing is actually very good for everyone and I hope it doesn't get thrown out by some reckless legislation-writing.
What happens in practice that there are only so many grocery stores where consumers can choose to shop thanks to corporate mergers and lax antitrust enforcement. So if all of them raise their prices at the same time then those consumers are out of luck.
Now technically it would be illegal for the grocery stores to collude in price fixing like that, but they'll hide behind the fact that all of them will buy their surveillance pricing data from Google [1].
Google will tell all of the competitors exactly how much they can charge you for your eggs, and you'll get the same price everywhere.
[1] https://www.thebignewsletter.com/p/will-google-organize-the-...
> the others would just do the same and compete away those margins once again, with the marginal gain being handed back to consumers
This is an assumption that doesn't necessarily have to happen. Some markets remain uncompetitive, otherwise you would see every market collapse to 0 margins if this were always true.
That's the ideal dream scenario, but in reality the market isn't that efficient. Lots of markets gouge their customers and due to power imbalances the customers can't really do anything about it. The free market solution to this is just generally to let people suffer.
I don't see why consumers wouldn't just pick the stores that have better prices for them. Why would they know/care/need to know what the prices are doing for other people?
You can't see you mean? Consumers pick things that are reasonably convenient, achievable and known to them. These things are all subject to exploitative tactics by grocery stores.
There's also price-fixing, which famously occurred in Canada recently.
Not to mention cornering a market like Walmart would and removing consumer choice entirely.
All of these are separate issues from dynamic pricing
You were not asking about dynamic pricing. You were asking why you weren't able to see the reason that consumers don't always find & choose the cheapest option. The person you were responding to was explaining the unethical realities of food retailers. There's no reason why these would disappear with dynamic pricing.
> If any store used dynamic pricing to expand their margins, the others would just do the same and compete away those margins once again, with the marginal gain being handed back to consumers.
How would you do it if pricing is dynamic and changes every day?
By the time competitor finds out about the price, you might have already reduced it, making it look like theirs is more expensive even after they applied discount.
Because the exact same is true in reverse
Dynamic pricing based on personal data is not even a market, let alone a perfectly competitive one. Temporal dynamic pricing can mean almost anything, so might be ok (early bird lunch deal) or pure evil (bottled water now costs $100 because there is lead in the tap water).
Your evil case is not evil
The point of pricing water to that level is that it would induce other people who have access to bottled water to bring it to that market, as is desirable
You assume that other people can simply bring bottled water to market & compete with discoverability and access to customers with established players?
Or is your point that all people in a market with leaded water should be paying $100 for pure water because it is inherently worth that much per the market.
No, I assume that if anyone can bring bottled water to market, they should have a strong incentive to do so whenever there is a strong need for more of it.
But they (everybody) can't. Bringing bottled water to market requires a clean source, rights to acquire it, and a manufacture & distribution network. Plus retailers. As well, these things are often blocked to newcomers because of existing deals with big players.