My last company had a code base originating in the 90's and they still write most parts of the GUI with a library that is a thin layer on top of Win32 API, with a self-rolled "ORM" for DB access (with LOTS of enums) and all that with >2million lines of C++ code. The code includes at least two implementations of std vector and std:list. One of which is even *named* std::vector. Feels good remembering that I have left that behind