The comment is wrong for C, but could be right for C++. The data structures in STL are all implemented as red-black trees. They can't be rewritten as B-trees because of some iterator/synchronization/backwards compatibility mess.

I once did a similar benchmark to the one in the article and found that Rust outperformed C++ because the C++ code was using the builtin std::map. But for reeeeeeally big datasets PostgreSQL beats them both so who cares. :p