I wonder: are Apple's designs just as data-driven?
My understanding (as an outsider who has heard some UI-related people from Apple talk) is that they iterate on their designs, but it's all in-house. There's no A/B testing going on, they make a decision based on experience and give that decision to the end-user.
Not only that, but they are masters of creating a 'design ecosystem'. Browse apple.com, then head to the apple store, its a seamless experience. This is arguably one of the competitive advantages that has helped Apple maintain it's position in the market and with consumers everywhere.