This is one of the core issues that make many ES systems complex. A service owns an event in the same sense that it owns internal state. It's internal to that s

This is one of the core issues that make many ES systems complex. A service owns an event in the same sense that it owns internal state. It's internal to that service and only expose what it finds appropriate, in the way it finds appropriate. That is almost never directly as an event on a public eventbus.