Iterators are inconsistent, but this plays to the strengths of C++'s duck-typed generics. The same code can either copy or insert, depending on whether you use std::begin or std::back_inserter; this isn't principled but it's powerful.

The "six types of iterators" overstates it. You don't need to sweat those details unless you are writing boost or something. Just add what you need.

I miss C++ iterators in other languages. For example, in Rust it's hard to talk about "a position in a String" which may be advanced or retreated. Usually you give up, use an integer index, and this is much worse.