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A night out could spoil your privacy, unless you pay cash

Paying with cash keeps your purchases private.

A night at the pub could backfire in more ways than you think. Besides waking up with a hangover, you may also have provided the government or insurance companies with data they can use in ways you might not like.

That’s because, as KTH’s expert on web privacy, Professor Gerald Q. “Chip” Maguire explains, you give up more than your money when you make purchases by mobile phone or bank card.

Maguire, who says he avoids even using a mobile phone and recommends paying in cash, points out that every non-cash transaction sends a new stream of personal data to, potentially, the government, insurance companies and anyone else who wants to know more about you.

Targeted marketing is the most visible sign that we’re being tracked, but Maguire sees another, more troubling trend. “The social control increases with the computerization of society,” he says.

“Merchants can target direct marketing to you, or sell information to others. But that’s not all. Maguire warns against what he calls “Homeland Health Care” — a reference to the U.S. Department of Homeland Security. Imagine the invasiveness of NSA data mining being applied to the health system. Health authorities can use your transactions data to make judgements about whether you’re risking your health by what you eat and drink.

But if that doesn’t bother you, remember that if the cash register at the pub is connected to the tax authority, as it is in Sweden and other countries, the government can assemble a record of your purchases and surreptitiously assess the accuracy of your income tax reporting.

Besides, when you pay with cash, you’re able to leave a tangible tip to your server. They might appreciate that.

David Callahan

Professor Gerald Q. “Chip” Maguire explains “Homeland Health Care in this video clip.

David Callahan
David Callahan is editor for international news and media at KTH Royal Institute of Technology.