This behavior isn't transparent. You don't know what the person in line before or after you is paying for the same products. There are companies already employing these techniques to rip you off.

Consumers are not free to choose where to get their goods. They are limited by practical restraints such as proximity and access. Food deserts exist in this country and they impact the lives of tens of millions of Americans. Millions live in food deserts and lack access to a vehicle.

You've also fallen for the myth that that just because competition could exist it means that industries will always act in ways that hurt their own profits in order to compete for each other's customers. History, and your own experience, should make it plain that this is a lie. Just because consumers want something doesn't mean that there will ever exist any company who will provide it, or provide it at scale, provide it to a comparable level of quality/utility, or provide it at a reasonable cost.

I want a cell phone carrier that doesn't collect and sell my personal information. They don't exist. I want a new car that doesn't come with computers, bluetooth, and any other high tech features. They don't exist. I want a streaming video service that offers every movie and TV show from the last 70 years for one low monthly rate. That doesn't exist.

The fact is that in our capitalist market consumer choice is severely limited by what the market has on offer. If something allows everyone in an industry to make money hand over fist they'll all implement that thing because it makes them vast amounts of money and their shareholders will demand that they do.

Consumers in the US are commonly unable to find a company willing to provide services that they want because in some cases it will always be more profitable for companies to not provide what consumers want.

If Personalized Dynamic Pricing makes grocery stores a fortune by screwing over their customers they will all implement it. Any weird one off co-op or independently run store that refuses will be of zero help to the vast majority of the population who cannot access it.

Regulations are a powerful tool that can be used to force companies to provide things for consumers that companies otherwise never would. Without regulations companies would be perfectly happy to sell people products that will kill them. Hell, even with regulations companies are often caught trying to sneak products filled with poisons like heavy metals into people's homes. You have personally benefited from regulations your entire life.

Sadly, they can also be abused by corporations who bribe politicians and infiltrate regulatory agencies so that they can keep out competitors, and that is a terrible thing, but of course the problem there isn't solved by making regulations impossible, but by getting rid of crooked politicians and forcing oversight onto agencies to ensure that they're working for the public good and not for the corporations.

Intervention is absolutely needed and we need much more of it, but we should be careful to make sure that they are the right interventions and that they are working to improve the lives of the people and not just the profits of the corporations who seek to exploit us at every opportunity.