Actually the article is correct. Accountants only care about the explicit cost (which is useful when calculating taxes) however Economists consider both the explicit and the implicit costs (the opportunity cost). E.g. you have a plot of land; the economic cost is how much you could be renting it out for (the opportunity cost).
Well then, like I said, I would love to see them try to calculate the unknowable potential of how many people who would not pay for the apps they pirated, would have paid if they had not pirated the app, (which they did). Aside from arbitrarily picking a percentage to multiply by several billion to yield an astronomical number that sounds good in a headline, that is.
If developers are upset about pirated apps, let me calculate how many more apps they'd sell if Apple and their suppliers would get off their lazy butts and make 100x as many iPhones every year. Apple is costing Developers billions! Not to mention how many people are donating money to charities which they'd otherwise spend on precious apps! Not to mention, global warming! Not to mention chevrolet not producing electric cars! God, think of the developers! All the unknown impacts on sales that never were! The whole world is conspiring against them.
You make a product, you put it out there. It's gonna get copied, knocked off in china, pirated, imitated, and eventually you're gonna fall off the back. You make the sales you can, work to provide a service that keeps your paid customers happy, and you work on your next big thing. Welcome to business, Developers. You're in the same boat the rest of us.
But the app store needs a trial process.
...and again, I personally do not pirate apps.