One thing missing from this discussion is that being a junior engineer often means you are inheriting someone else's code and, in general, a large number of ass

One thing missing from this discussion is that being a junior engineer often means you are inheriting someone else's code and, in general, a large number of assumptions or decisions. So a big part of the issue is that senior developers do not realize how many assumptions or system decisions are built into their system, and therefore do not realize they need to tell the new person about that stuff. So coming onboard can involve a lot of what amounts to mind reading. Sometimes things that actually are not the least bit obvious seem obvious to the senior person, so they may indicate (inadvertently) in their tone of response to a question about them that it was a dumb question. And so that makes the new dev try harder to figure out what the assumptions are without asking.