Lehman's premise is faulty, which deflates his entire stance. There was a time when you—and everyone—had no idea what you were getting for your $4 at Starbucks. Or Dunkin' Donuts. Or Caribou Coffee. Or McDonalds. Or Intelligentsia.
Even if you frequent Starbucks on a regular basis, you have no idea what you're getting each time you pay $4 for your Caramel Macchiato or $2 for plain ol' coffee. It could be a different day, a different Starbucks, a different roast, or a different barista who's having a dreadful morning and, for now, just doesn't have their head in the game.
Now, one could argue that the App Store experience is less like a coffee shop, and much more akin to shopping at a purveyor of brands like Macy's, where multiple companies make the same type of product and vie for your dollar by competing in myriad ways. But much is still the same: the typical customer has no idea what kind of craftmanship went into a pair of jeans, an iPhone game, a gourmet coffee drink, a perfume, an iPad task manager, or a piece of luggage. Typically, our only chance at truly finding out whether the product is a good fit is simply to take the plunge and buy it.
You may have no idea what you're getting for your 99¢, $2.99, $9.99, or more. Or perhaps you do—maybe you recognize the developer because you've already bought from them, much like you may recognize the name of the coffee shop you just walked into. Or perhaps you're an informed consumer who read a glowing review from one of your favorite, trusted authors. But even then, the developer you're familiar with may have slipped on this new app, or your favorite reviewer could have missed some important shortcomings because they don't have the same needs or workflow as you.
The analogy still stands, and well: it's ludicrous that some people have no problem taking a chance on a $4 cup of coffee that may or may not be enjoyable, yet balk at spending what is really a pittance on an app that may offer longstanding value or possibly even change their life.