The power of vertical integration means that Apple could sell their hardware at a loss, to get you inside the Walled Garden TM and then keep 30% of all you spend inside it.
I'm not saying they do that, considering how much their products cost, I'm saying they could. That's what vertical integration brings to their table, above all else.
They give away their software but get a 30% on the software made by other companies and do their best not to let those companies get paid by other means than Apple's stores. I think this was the point of GP.
> "They give away their software but get a 30% on the software made by other companies"
Not on Mac they don't. macOS isn't tied to the App Store in the same way that iOS devices are, and it probably accounts for a tiny percentage of third-party Mac software sales by value.
I'm not saying they do that, considering how much their products cost, I'm saying they could. That's what vertical integration brings to their table, above all else.