Because of everything you've outlined in your last paragraph and more, I don't know many competent C++ programmers who would call std::string or std::map "zero

Because of everything you've outlined in your last paragraph and more, I don't know many competent C++ programmers who would call std::string or std::map "zero cost abstractions" with a straight face. That term is more commonly applied to things like CRTP, template policy classes and other abstractions that you pay for in compile time (and, depending on linker optimizations, code bloat), but not in runtime [1]. As you point out, an abstraction that does a bunch of extra work is by definition not zero cost. [1] Yes, code bloat can lead to runtime performance issues as well. Common sense coupled with linker optimizations can usually, but not always, mitigate those issues.