Bad User Interfaces in Every Day Life ... or How The Vending Machine Nearly Stole My Money 

23 Jul 2004

Like most offices, we've got a vending machine in our kitchen filled with various types of (mostly) edible stuff. And like most people too lazy to make breakfast and with little regard for my health, I'll often grab something from the vending machine in the morning if I'm hungry.

Today, I decided I wanted some breakfast and headed to the vending machine to grab my usual Frosted Cinnamon and Brown Sugar Pop Tarts. I do have to say, however, I got a little bit excited when I saw that we had some new items in the vending machine. I quickly scanned the rows and found my breakfast - a Nature Valley Frosted Vanilla Yogurt Granola Bar.

I threw in my 60 cents, looked at the item number - E10 - and started to punch in the code. E, then 1 ... well, thankfully I realized that as soon as I pressed 1 I would be getting whatever was in slot E1. Looking more closely, it turns out there's a button for the number 10 on the vending machine.

Why in the world would you do that? How natural is it to look for a button labeled with a '10' when the item number is E10? Isn't your first instinct to hit E-1-0?

Making it more egregious, there's no E0! Now, I understand folks who've never programmed don't always grasp the concept of an index starting with 0, but I really think most people could conceptually understand a vending machine that went from E-1 to E-0 or E-0 to E-9. I have to think either of those would be infinitely preferable to E-1 through E-10.

All of this got me wondering if vending machine interfaces go through some level of UI testing, or if the low cost of making a mistake (usually less than a dollar) and the either very captive or very temporary audience allow the vending machine company to not worry about lost sales?

Personally, I think it's a huge conspiracy, meant to steal an extra 60 cents from people every day. Think about it. Some company has thousands of vending machines (let's say 10000) out in an area and places completely opposite items in the 1 and 10 columns of each row. Like a granola bar on one end and a pixy stick on the other. If one person spent an extra 60 cents a day due to mistakenly buying the item in column 1 instead of column 10, that could add up to $6000 each day (gross). Even if they only make a small profit off of that (let's say 10%), it's still an extra $600/day. We're talking about an extra $150,000/year (using about 240 workdays/year - I have no idea if that's accurate).

Of course, it gets even scarier when you realize that there's a huge vending machine monopoly run by a Saudi-owned corporation. And that corporation is one of the biggest contributors to the Bush family. With millions of vending machines all stealing 60 cents a day, it's no wonder the Bush campaign has seemingly bottomless pockets.

(Ok, I made up the last part about the Saudis/Bush and the vending machine conspiracy. But, is it really that implausible?)