The Economics of Mobile Payments: Why Phones Are Replacing Cash in the UK

Phones are replacing cash and cards in the UK because mobile payments lower transaction costs and benefit from network effects, becoming more useful the more widely they are adopted. Many people now pay for shopping, bus fares and lunch with a tap of a phone, often carrying no cash or cards at all. Yet cash has not disappeared, and economics explains both the rapid spread of mobile payments and its limits.

How Mobile Payments Lower Transaction Costs

Transaction costs are the time, effort and money involved in completing an exchange, beyond the price of the good itself. Cash carries many of them. Retailers must manage cash by counting it, depositing it at a bank and managing the risks of theft and counting errors. Credit and debit cards reduce some of this work for retail staff, but they introduce other costs, including card-processing fees and the equipment needed to accept payments.

Mobile wallets reduce the effort further. A fingerprint or face scan confirms a payment in seconds, shortening queues and simplifying record-keeping. The savings vary between businesses, however. A small independent shop may face payment terminal and service costs that a large chain can spread across thousands of transactions.

How Network Effects Drive Mobile Payment Adoption in the UK

Payment systems are a classic example of network effects, where a service becomes more valuable as more people use it. More specifically, they form a two-sided market: a platform connecting two distinct groups, here shoppers and retailers. A digital wallet is of little use if shops will not accept it, and shops have little reason to support a method few customers use.

Once acceptance reaches a certain level, a self-reinforcing cycle develops: more retailers attract more users, while growing user numbers encourage additional retailers to adopt the payment system. The UK shows how quickly this can happen. According to Whop, which compiles figures from UK Finance, 57% of UK adults were registered for at least one mobile payment service in 2024, up from 42% in 2023.

Network effects can also concentrate a market. The same data show Apple Pay accounting for around half of UK mobile wallet use. When one or two platforms dominate a two-sided market, economists watch closely for market power, since a dominant platform may set terms that rivals and retailers find hard to resist.

Mobile Payment Fees: Who Pays in a Two-Sided Market?

Consumers typically pay no direct fee when using a mobile wallet, but several parties may be involved in processing a transaction, including the merchant's bank, the consumer's bank, the card network, the payment processor, and the wallet provider. You will continue to incur the same merchant fees as you normally would. The only change is in how payments are validated using mobile wallets; the costs incurred by using the underlying credit or debit card remain unchanged.

This pattern is typical of two-sided markets. Platforms often charge one side little or nothing to attract users and recover costs from the other. Shoppers usually pay nothing directly, while retailers pay fees that are ultimately reflected in prices for everyone, including customers who pay with cash.

How Mobile Payments Change Spending Behaviour

When a payment takes two seconds rather than thirty, consumers may make small purchases with less deliberation. Behavioural economists Drazen Prelec and George Loewenstein described a “pain of paying”: handing over cash makes a purchase feel real. Digital payments weaken that link, which can encourage overspending on small, frequent purchases. Spending alerts and budgeting tools can help restore some of that awareness.

Why Cash Still Matters in a Cashless Society

A fully cashless society remains some way off. Not everyone owns a compatible smartphone, has reliable internet access or feels comfortable with digital banking. Older people, those with limited digital skills and people without a standard bank account rely more heavily on cash.

Cash also works when technology fails. Keynes’s theory of liquidity preference identifies a precautionary motive for holding money in case of emergencies, and during a power cut or network outage, notes and coins still complete a sale. Cash also offers a degree of privacy that electronic payments do not.

Will Mobile Payments Replace Cash in the UK?

Mobile payments introduce additional security risks. Although tokenisation and biometric authentication can make transactions more secure by protecting payment details, users remain vulnerable to phishing, hacking and account takeover. Trust is essential to the adoption of mobile payments. If users lose confidence in a payment platform's security, its network effects could weaken as quickly as they developed.

The likely outcome is a mixed system rather than a single winner. Supporters of rapid digitisation point to lower costs and faster payments. Critics argue that relying entirely on digital systems would exclude vulnerable groups and leave the economy exposed when technology fails. Which methods prevail will depend on cost, security, access and the economic value each delivers.