The "passages" shown on the chart images
are definitely steel boat
territory for the adventurous and then with tide equal to draft
The paper charts I used to use had a reliability
diagram with an explanation of how the estimate of reliability
was arrived at. I don't recall
that they had any guarantee that they had identified every rock and shoal. What the explanation provided was the details of the bathymetric survey
such as the number of survey
lines carried out. The cost of identifying every rock and shoal would be enormous.
That being said there are a set of charts of the Western Australian coast between Bunbury and Geraldton which were published by their Marine
and Harbours Department which did a very good job of it. However it used to drive me nuts having to change charts every hour or so. I think they used a combination of bathymetric and aerial and satellite
surveys to compile them, there are very few rivers and the water
is very clear in that area of coast.