Parking meters are typically irksome to use in whatever guise they take. This, one of the latest generation of Sydney parking meters, I find particularly annoying.

There are two ways to pay. One is with coins, the other with a credit or pre-pay card. Arranged around the liquid crystal display (which is completely illegible at night despite the faint LED lighting) are four buttons: minus, plus, cancel and P.

To pay by credit card, you press the plus button until you have the desired end time, then press the P button and insert your card to pay. Because each parking spot is priced differently in Sydney this is a very handy function. It helps you get an idea of what the parking will cost before committing to it.

Naturally, when you want to pay cash you want to use the same function, for instance to find out whether the shrapnel in your wallet will suffice.

The problem is that once you’ve used the plus and minus buttons to set a time and are happy (well, not happy as such) with the cost, you cannot enter coins into the slot. It is simply blocked. No explanation why, you just can’t put any cash in the machine. To do so, you’ll first have to hit the cancel button, but the machine doesn’t tell you that.

Why block the coin slot in the first place?

Nothing much, just one of life’s little UX annoyances.