The products you mentioned are prime examples of Louis Sullivan's "form follows function" dictum. Although it can be argued that in all four cases, classical design principles such as symmetry and geometric ratios were followed, thereby defining a specific style.
Style is actually intrinsic to design as it is defined to be the resultant embodiment of a set of design primitives (vocabulary) as transformed by a set of rules (grammar). The end product thus will generally exhibit characteristics of said primitives and grammar, thereby defining a specific style.
As master artists (architects, painters, poets, songwriters) as wont to have well-defined vocabularies and grammars, their respective bodies of works are generally instantaneously recognizable by the style. An example would be Jose Mari Chan's songs - if you are familiar with his compositions, you will easily recognize them. Another would be Frank Lloyd Wright's prairie houses. And of course, e.e. cummings' poetry.
Because they share the same design primitives, the H1's successors, H2 and H3, are instantly recognizable as succeeding iterations of the line. Or in layman's terms, they follow the same style.





