But in a competitive environment, dynamic pricing can also lead to price wars that benefit consumers.

Most companies use the strategy to try to broaden their reach, according to pricing experts, increasing their revenues by bringing in new customers rather than making more money on each one.

Take airlines for example: Lowering fares far in advance allows more price-sensitive, date-flexible leisure travelers to afford the trip, while business travelers pay much more for last-minute tickets.

In those cases, merchants create a proxy for the types of people who will pay more to eat or fly.

Using that information directly can be even more valuable since it can allow firms to offer prices tailored to what it would take each individual or groups of people with similar characteristics to make a purchase.

Companies now have vast troves of data about their customers and direct connections with them through smartphone apps that can be used to target prices.

If companies did this more often, they might end up charging wealthier people more, effectively creating a progressive cost structure for goods and services.

For example, a 2017 economics paper found that grocery stores can make more money by offering lower prices in poor neighborhoods, which they currently tend not to do.

It's also clearly legal; the Federal Trade Commission wrote in 2018 that "absent unfair and deceptive conduct, personalizing price itself provides no basis for intervention."

But few companies have embraced the strategy, fearing the kind of fury that Wendy's faced - or, at least, don't charge different sticker prices for different people, which draws accusations of the uglier term "price discrimination."