Nick Nadeau recently bought a hard drive through Walmart’s app—and got a bad feeling about its price.

On Nadeau’s phone, Walmart listed the drive for $369. On his wife’s phone, however, the drive cost $110 less.

“They are using cookies or stored data against me,” Nadeau, 38, a product manager at a technology company, thought.

Call this AI-induced price anxiety. American shoppers are convinced that businesses—including retailers, restaurants, ride-shares and grocers—are deploying technology to charge higher prices. They worry that businesses are using artificial intelligence and other technology to quickly change prices by assessing their needs or profile.

Walmart, Kroger and McDonald’s are among companies that say they aren’t doing this. Walmart went so far as to issue a letter from its chief executive last month saying it doesn’t price products based on who is buying or sudden need.

Yet the denials have failed to stanch the concerns of shoppers and consumer activists. On social media, posts complain that stores are using AI in combination with digital shelf tags to track shoppers’ interest and make sudden or personalized price changes.

As the complaints have risen, several states have passed laws restricting data-driven pricing or requiring companies to disclose use of algorithmic pricing. Earlier this month, a customer filed a lawsuit against McDonald’s that alleges “algorithmic price-fixing” of menu items. McDonald’s said the lawsuit is “filled with inaccuracies.”Nadeau, who lives in Belleville, Ill., wound up buying the hard drive at the lower price his wife found using her phone, but he was alarmed by the experience. “It just felt invasive,” he said.

A spokeswoman for Walmart said the prices varied because of an error that has been corrected, not because it used personal information to calibrate the price of a product.

Adjusting prices based on demand or time of purchase—sometimes referred to as surge, dynamic or personalized pricing—isn’t new. For years, airlines, hotels and ride-share companies such as Uber have done so.

Likewise, retailers have long moved prices around to reflect rising costs or maximize profits. Some retailer loyalty programs offer different discounts to different shoppers based on their purchase history or personal attributes. Discounts based on being a student or senior are also common.

Yet consumers are especially sensitive now to anything that drives prices higher, because inflation is squeezing their pocketbooks. Over the past six years, overall prices as measured by the consumer-price index have risen more than 29%.

“Then you add to that the anxiety around AI,” said Jameson Spivack, who focuses on AI governance issues for the Future of Privacy Forum, a nonprofit that works with member companies, including Walmart and Apple, on technology-privacy issues.

Using data to set prices isn’t new, Spivack said, but companies now have much more data about individual consumers that they can use when setting prices. In addition, they have new tools to quickly change prices online or in stores.

Much current angst is focused on electronic shelf labels, which have replaced the printed labels that dotted shelves at groceries and other stores. Research on digital shelf labels in the U.S. and Europe, where grocers have widely used the technology for more than a decade, found the labels don’t lead to surge pricing, in part because price changes are obvious to anyone walking by. Rather, research found, grocers have used the labels to discount goods that are about to expire, reducing food waste. Retailers say they use digital labels to save time on paper tag changes.

The electronic labels have enabled some grocers in certain European markets to entice shoppers by discounting prices hundreds of times a week. For the most part, however, stores raise prices overnight or at regular intervals such as Monday mornings. Walmart said it typically changes digital price tags when stores are closed, in part because it doesn’t want to confuse shoppers.

Companies have nevertheless drawn fire from consumer advocates and some politicians for taking out patents on technology and collecting growing quantities of personal data that, the critics say, lay the groundwork to deploy more sophisticated dynamic or personalized prices in the future.

Under scrutiny, some companies, including grocery-ordering service Instacart, have backed away from experiments with variable pricing.

This month, McDonald’s said its franchisees don’t use artificial intelligence to set menu prices or change prices based on real-time conditions or demand. “There has been inaccurate reporting about how menu prices are set,” said the company.

Walmart Chief Executive John Furner published a letter to customers last month saying prices change, but that Walmart won’t use someone’s income, shopping history, or moment of need to charge more. “We price the product, not the person,” he said.

After the letter failed to quell criticism, Walmart’s head of corporate affairs, Dan Bartlett, published a letter addressed to a consumer advocate at the nonprofit Groundwork Collaborative. Leaders of the nonprofit have said Walmart’s patents and technology could enable the use of personal data to raise prices.

“Your recent public statements repeatedly mischaracterize Walmart’s pricing practices,” Bartlett said. He also echoed the CEO’s earlier denial.

In response, Groundwork Collaborative called on Walmart to withdraw some of its patents. “A patent isn’t a plan,” said a Walmart spokeswoman. Walmart won’t use or renew one of the patents that has garnered scrutiny, she said.

New York last year passed a bill that requires companies to disclose when they have used algorithmic pricing on a product. This year, Maryland, Connecticut and New Jersey passed laws restricting certain types of personalized or data-driven pricing.

“New Jersey families are already feeling the pressure of higher costs. The last thing they need is companies secretly using their personal data to charge them more than someone else for the exact same product,” Gov. Mikie Sherrill said when the state law was signed.

Dozens of states are considering a variety of bills that would prohibit or regulate the use of personal data or real-time demand inputs, such as weather, to set higher prices.

This summer, the Federal Trade Commission issued a proposed enforcement policy statement aiming to penalize companies for “any deceptive or unfair personalized pricing,” particularly “where consumers reasonably expect that prices for a product or service will not vary based on their personal data.”Colorado Gov. Jared Polis, a Democrat, earlier this year vetoed a bill that would have made it illegal for companies to use personal data to set individualized wages or prices. “Because of the broad sweep, the bill would punish differentially lower prices, not just higher prices,” Polis said.