Imagine you are looking for a flight to Mallorca, you open the same booking website as your neighbor – and suddenly find yourself paying significantly more than she does. The travel time, number of passengers, and destination are the same, but not the price that a machine has calculated for you. What sounds like science fiction has long been everyday fact in online retail, and it is becoming more complex. Klaus Wiedemann, a legal scholar, has systematically investigated this phenomenon in a recent article. He comes to an alarming conclusion.
Unpredictable Prices
The key difference lies in the process behind the pricing. With so-called “dynamic pricing”, all customers see the same price at the same time – it fluctuates based on demand, inventory, and the competitive situation, but it is the same for everyone. Not so with personalized pricing: here, the price depends on the specific characteristics of the individual – their purchase history, their surfing behavior, the device they use, or whether they have accessed the website via a search engine or a price comparison portal. In some cases, the stated goal of the algorithm is to get as close as possible to the highest amount that this person would be willing to pay at that moment. At the same time, the system takes into account the prices charged by other providers.
AI-based systems go further than classic algorithms: they are only given an abstract goal – such as “maximize profit” – which they then independently develop strategies to achieve. They learn from experience, optimize themselves autonomously, and their mechanics are so complex that even the companies that use them can no longer explain why a certain price appears on the screen in the end. The OECD already summed up this problem in 2017: such an algorithm delivers an optimal result without revealing the underlying decision-making steps.
What the Law Does Today – And Where Its Limits Lie
What protects us legally? There is no general obligation to disclose price calculations. However, if a price has been personalized on the basis of automated data processing, the provider must provide pre-contractual information about this in distance selling contracts. According to Wiedemann, anyone who uses personal data for pricing purposes also needs the active consent of the data subjects – a mere mention in the small print is not sufficient. But Wiedemann clearly sees the limits of this information model: Who actually reads every privacy policy? The protection offered by the law today primarily benefits those who are actively interested in information.
In the end, the fundamental question remains unanswered: Do AI-supported pricing systems lead to more competition and lower prices for everyone – or does the wealth flow one-sidedly to those who own and operate the algorithms? Time will tell whether today's instruments will suffice when price personalization is no longer the exception but the rule. Until then, it is worth pausing for a moment before clicking “Buy now” and asking yourself: Is this price really mine?
Klaus Wiedemann
Die Preisfrage – KI-basierte Preissetzungsmethoden im europäischen Wettbewerbs- und Verbraucherrecht der Digitalwirtschaft
Zeitschrift für Europäisches Privatrecht 34, 1 (2026), 12 – 38