I would say that you've paid the opportunity cost of learning the interlocking systems that compose into your application, and the processes required to update, test, and deploy it. This composition occurs across various boundaries, inside and outside the process, the network, and so on.

The FAANG-ist is one that can pay that opportunity cost quickly and completely, such that they are able to reason about the system with confidence, particularly when it comes time to reverse a feature or bug request into a set of commits. Or, more likely, a set of experiments and commits based on the outcome of those experiments. Given that there is no unified language of application design, doing this requires detailed, specific knowledge of every sub-system involved, the abstractions their authors used, and the ability to translate between them such that you can imagine the entire causal change from input to output. This is hard, and it's why you make the big bucks. (Interestingly, I first wrote "bugs" instead of "bucks". :)