There are three data structures unsystematically blended into one (that is, one cannot unambiguously tell which fields go into which "virtual" type, and cannot formally check the correctness). The name thing_t is indicative that you indeed cannot really tell what that entity is. This kind of data structure design begs for errors, while being conceptually wrong.
I get your point, but how to tell "labelling" from typing? Typing depends on semantics. This particular example only works out because the types are all strings, which is a case of sort of loose typing often used in programming. It could've been like this:
