A recurring theme of this blog is that, while the "direction of travel" should always be towards simplicity, the process of simplifying involves accepting that a degree of complexity will often be unavoidable. The art of simplification is knowing where to draw the line beyond which nothing more can be taken away without negative effects. Hence: As simple as possible, as complex as necessary.

Examples of unnecessary complexity are all too common, not just in web development, but excessive simplicity can be a problem too—the "gravity-operated" motorised pepper mill, for instance.

Unintended consequences

Contactless payment cards are another example of technological innovation where it seems to me the balance between simplicity and complexity has not been properly weighed.

If your card is "contactless" it will have a "radio waves" symbol on it and the aim is to encourage you to spend more by making it simple and quick to pay for things. You just place it on or near the merchant's terminal and the money is taken without needing to enter a PIN or any other form of authentication or authorisation.

Quick and easy to pay for things when that's what you intend, certainly, but easier too for things you don't mean to happen.

Fraud and electronic pickpocketing might seem the obvious dangers, but proponents stress the security and fraud mitigation measures around the technology (including limiting the amount that can be spent to £20 in the UK, and periodically requiring the PIN), and to be fair, instances of fraud appear to be rare so far.

Of more concern are the inconveniences this "convenient" technology introduces.

Card clash

For a decade now, users of London's transport network have increasingly paid for their journeys using another contactless method: the Oyster card. You load the card with credit which is then deducted at the appropriate rate by touching terminals at either end of your journey, or in the case of buses, as you enter only. Undoubtedly a more efficient payment system than cash, Oyster has made boarding queues largely a thing of the past.

Recently the terminals on London buses were changed to allow contactless payment cards to be used as an alternative to Oyster. A warning was issued to Oyster users not to present both types of card to the terminals. You wouldn't be double-charged if you did, but the system would cancel the operation being unsure which card you wanted debited.

Simpler for whom?

At about the same time, without asking, my bank replaced my expiring debit card with a contactless one.

Like many Londoners I'd always just touched my entire wallet containing my Oyster and debit cards onto the terminal. Doing so now risked the ire of my fellow passengers as the confused terminal refused to take payment from either card. So I was forced back into the inconvenience of having to take the card out of and return it to my wallet, taking care to keep the latter well away from the terminal.

Not simpler for me.

A recent BBC report highlights cases where customers of major retailers have in fact ended up being charged multiple times as a result of inadvertently passing a contactless card near a terminal while paying with a normal chip-and-pin card.

I wrote to my bank asking them to switch me back to a non-contactless debit card, but they claimed they were unable to do this despite several other banks apparently offering their customers this choice. Making all of their cards contactless is of course simpler for them.

Regaining control

Simplicity and control are closely connected. One way of re-asserting control over your cards is to buy a specially coated sleeve which blocks the NFC signals.

As well as the small additional expense (under £10), this also means having to unsheathe, then re-sheathe the card whenever I want to use it. But at least my bus journeys are simpler and the potential for contactless mishaps (or worse) is removed.

Perhaps this all merely amounts to teething trouble with a technology we will all soon take for granted.

In the meantime, I shall continue to regard contactless payment cards as annoyingly, if not dangerously simple.