> Hide internal structure (that "private" is the default in C++, Java and Rust just adds to boilerplate; the default case is that you want everything public (unless you like writing trivial getters and setters just for the fun of it); legitimate uses of "private" exist, but are rare)

This is such a strange POV to me. There are cases where your classes are just data records, but any object with logic surely wants to restrict access to its state so it can maintain invariants? E.g. the simplest classes I can think of, like a vector that consists of a pointer to a buffer, a length and a capacity, wouldn't want to provide a setter for the buffer, or allow callers to set it to a random value?