Actually, IMO, a TIP is not. When you go out to dinner and you have a great experience, you CHOOSE to tip well. However, lets say your experience is horrible, again you CHOOSE not to tip.
Actually, not's not entirely true. Lets look at Audible for a minute. You can't purchase any Audible book via the app on the iPhone/iPad, etc, but you can purchase it any where else, including via Safari on your iPhone (do it all the time). Once you do, you can then download that same book to the iPhone. This is the problem I have in general with Apple's 30% TAX on IAP. It is exactly that a TAX.
I have purchase plenty from Amazon.com app, Sears App, BestBuy app. If apple was taking a 30% cut, we would not have these apps.
What infrastructure? You mean the one that stores they app? Allows the app to be downloaded. Doesn't the developer already pay a YEARLY fee? This 30% Apple cut is just a TAX, it's that simple.
Absolutely they do. My step daughter is a waitress, every year, her TIPS are on her W2 and they are taxed.