ST:Picard showed that Earth basically had a public transporter network around the world. It is how Picard goes from his vineyard in France to Starfleet headquarters. So, it isn’t all car flying cities.
However, if these are the people making decisions to deploy resources, why would they think of having ground vehicles at all? The only reason why the dune buggy was in Nemesis was because Patrick Stewart wanted it. Otherwise, it doesn’t really make sense.
A few years ago, I had to tell someone to convert some pictures since they took them in .heic and being able to see them wasn’t standard. Their response was to manually change the file extension on each of hundreds of files from .heic to .jpeg.
I think there was even an episode in Enterprise? where an old Klingon lamented that modern Klingon society went too far towards being warriors that they were starting to neglect other parts of society. Hell, Ezri Dax was right that, by the time of the Dominion War, the Klingon Empire was in need of serious reform.
And if anything, the Klingons seemed like they had a larger empire for a while, well before humans even went to warp. It could just be that they went into atrophy for long enough that allowed the Federation to fill the void by Kirk’s time.
After the War of 1812, the UK started to recognize the USA as a local power it had to deal with diplomaticly instead of with war. This gets shown in the negotiation of the 49th parallel and its maintaining of the Monroe Doctrine. Hell, the USA almost declared war against France after the Civil War to liberate Mexico.
Post World War I, the UK seemed to be the better ally. The UK was more willing to let the USA expand into core imperial territories during and after World War II. The USA didn’t have to fight a post British imperial war like it did for France in Vietnam. You also had the UK fall in line in NATO while France didn’t.
France would have been the better natural ally, but things change over time.