A proper database can be implemented in python -- I've done it -- but that doesn't make it a systems language. A "systems language" comes with the strong implication that it is possible to write an implementation of most software that is competitive with the state-of-the-art in terms of performance, efficiency, and/or scalability. That is only possible in languages like C, C++, Rust, and similar, hence the "systems language" tag.

Languages that are not systems language trade-off this capability for other benefits like concise expressiveness and ease of use.