What do you make of Shelley's futuristic world in The Last Man?

Mary Shelley's vision of the future in The Last Man is obviously quite different from what reality turned out to be. Her futuristic Europe still features horse-drawn carriages and early nineteenth-century technologies, as well as many a government ruled by monarchies. Characters still seem to dress and speak as they did in Shelley's own time. Between the 1820s and the 2070s, little seems to have changed in terms of culture.
Unlike later science-fiction writers such as Jules Verne (who wrote an elaborate dystopian future setting in his long-unpublished novel Paris in the Twentieth Century), Shelley does not seem interested in wondering what the future will be like so much as exploring a certain concept: what would happen if mankind were slowly wiped out, leaving a single person alone? Because Shelley is more interested in the philosophical underpinnings of such a situation and exploring the effects of grief and loneliness, she does not dedicate as much time to elaborate world-building.