T3 has an extended interview with Schiller:

“At the surface level, it’s an incredibly simple product. But the reality is it’s actually an incredibly complex product to make. Each AirPod really is its own computer, running software and hardware. And those two computers need to deliver this very clear experience that you want, and they have to work together, because we’re very attuned to synchronisation in audio as a species. And so it has to work the way you want.

It takes considerable time and effort to make something feel simple. This is true when it comes to software, and it’s often more true for hardware. The fact that the AirPods have such a seamless audio experience almost every single time you use them is not a side effect of Apple just making them simple, it’s because they did a lot of complex work to make them seem simple.