I don't disagree in general. Although, as a founder, I can tell that in practice providing first-class documentation is less trivial than it sounds. Not everybody has the Apple's or Google's money. Technical writers are not cheap. Also technical writers tend to have problems understanding how a system works, because they lack the knowledge of the system's internal logic. Therefore, developers should be involved in writing documentation too which makes it even more expensive and tedious process. Then software changes and documentation has to be partially rewritten again.
All in all, not every car is a Mercedes and not so many people can afford a Mercedes. Companies frequently don't provide best-in-class API documentation not because they are lazy (although it can happen too), but because it's always a trade-off: should the money be spent on improving documentation, or invested into new features. It's a matter of priorities and balancing between them. For some products API is the top priority, for some isn't.
All in all, not every car is a Mercedes and not so many people can afford a Mercedes. Companies frequently don't provide best-in-class API documentation not because they are lazy (although it can happen too), but because it's always a trade-off: should the money be spent on improving documentation, or invested into new features. It's a matter of priorities and balancing between them. For some products API is the top priority, for some isn't.