Well, to me it's like the way Shakespeare, e e cummings, and Kool Keith all write in the same language.
Context switching between working on work codebase, Chromium code base, and various third party C++ codebases is a headache as much for their basic differences in coding style (use of whitespace, capitalization, naming, etc.) as for their wildly varying build/metabuild processes.
And of course, each implements and then extensively uses their own library features like reference-counted pointers, managed GC pointers, collection data structures, iterator-like abstractions, etc.
Context switching between working on work codebase, Chromium code base, and various third party C++ codebases is a headache as much for their basic differences in coding style (use of whitespace, capitalization, naming, etc.) as for their wildly varying build/metabuild processes.
And of course, each implements and then extensively uses their own library features like reference-counted pointers, managed GC pointers, collection data structures, iterator-like abstractions, etc.