It is easy to find articles and guides designed for laypeople. If you know the right keyword, it is just as easy to find professional/expert level papers and articles. I have noticed that this is the case across fields. Is that what other folks experience? Where do you go for information when laypeople articles are too basic, but every expert level article is beyond you?
As a scientist, for me this gap was bridged by doing a Masters/PhD.
In my field, learning involves performing experiments using very expensive equipment and potentially very expensive failures. One also needs to spend a lot of time doing things that will build their own value (like reading papers and manuals and performing failed experiments) without necessarily producing a valuable output in the short term. It is difficult to do these things on your own without help and financial support from academia or industry. One would need to be in a very privileged position to be able to bridge the gap on their own.
I see where you’re coming from. There are a lot of shades of expert. In my estimation Masters/PhDs are already experts in their fields. They might not be the preeminent expert and have vast amounts to learn, but that knowlege base would likely put their knowledge at more than a step or two above a layperson’s. It would be a little silly to expect to gain that depth of knowledge without committing a whole lot of time and focus. Did I understand your point or did it go whizzing by me?
Put on the same scale - I was thinking more at first-year-in-a-major level information. Which would point straight at text books for anything that has an academic path and other subject matter books for things without standard classes like Jeffrey said in another reply. Do you have any other ideas?