Undefined behavior and safety issues in core language features
8/10 HighC++ is extremely unsafe, supporting all undefined behaviors from C (buffer overflows, pointer misuse) plus new undefined behavior from templates (invisible specializations). Iterator invalidation creates dangerous undefined behavior, and complexity makes it difficult for developers to understand what code actually does or prove correctness, increasing defect rates.
Collection History
C++ doesn't reduce safety-vs-anything trade-off since it's extremely unsafe (it "supports" all the undefined behavior of C like buffer overflows, adds many new scenarios with undefined result like invisibility of template specializations at the point of usage... One big problem is that iterators often deal with heap allocated data in the C++ containers and become invalid if the data is independently moved by the containers