I read a few of the responses in this thread, and as a so called "Yank" - I find it perhaps amusing that the whole point of the phrase was essentially "short hand" for describing a given mindset. Yes, "Yanks" who run their campaigns at home in "Yankland" will tend to ascribe to the culture they were born in - and take it from there. Others may well say "well, prior to the entrance in two world wars, the industrialization and military vigor helped to turn the tide against certain foes. Others more cynical may well suggest that any enemy force that is over extended is doomed to defeat - that the Yanks who arrived just made that collapse all the quicker. As one show writer wrote "there is his story, her story, and then there is the Truth". I'm sure the truth lies midway between opposing mindsets and stories no?
In the end? I'm more interested in the fact that the rules as depicted in the Third Imperium and the background written for it, along with AGENT OF THE IMPERIUM (in which the Iridium Throne orders the execution or annihilation of an entire world - without any resort to legal means - suggests that Marc Miller understands one of the reasons why the the Imperium as written can not exist.
Point the first: No human political power has ever been able to avoid the issue of "self-interest" for any ruling agency within a government. The Rich will always maneuver to insure that they remain wealthy and powerful, while the lesser mortals are kept in their place. It doesn't matter if you call the lesser mortals the plebeians, the proletariat, or tax payers. Those who rule make certain they continue to rule.
Point the second: culture is how individuals within a group of people bound together in society - educate the next generation on how to live. Culture dictates what is right, wrong, or morally ambivalent. It is also about how to prepare food that won't kill your family (hence local cuisine) or is relatively cheap to produce etc. In it also how the people are told what to expect where it comes to romance and formation of families or relationships. If you don't understand this point - listen to the music of the 1950's and contrast compare them against the popular music of say, the 2020's. Roles are defined culturally (what is a man's role, what is a woman's role, etc). You can NOT have enclaves of Imperial culture on a world that unites entire worlds together unless one of two things is happening - A) the rulers impose their culture on the lesser people or B) The Imperials have MORE people engaging in Imperial Cultural practices and hold dominance due to numbers. If Chinese History tells us anything (as did Gaelic history in France) - small groups of "elites" eventually vanish into the more populous culture than imposing their culture on the larger population. Early French cultures were conquered - but the victors vanished into the local culture and life moved on. So - how does the Third Imperium spread its culture? With slogans? With coercion? By granting Imperials certain superior rights over the non-Imperials? **Shrug**
Combine points 1 and 2 together, and you have the final problem that "each world is equal of any other in theory - each world's government is sovereign...
Either the Third Imperium has the ability to force its will on others or it doesn't. Marc Miller's AGENT OF THE IMPERIUM shows that it not only does have that ability, but actively uses it. If you sterilize a world, and the rest of the Imperium finds out about it - what do you think that would do to their relationship with the Iridium Throne? If the Iridium Thone is willing to do that, one might suspect that it has sufficient military force to put down those who might riot against it.
So - shorthand wise? Yanks In Space? Sure. Russians in Space? Just as valid as Yanks in Space. How about Romans in Space? That works - as short hand - provided both you as the speaker and you as the reader know what each terminology means. Google "7 blind men and an elephant" and then apply that parable to the description of the Third Imperium by 7 different writes all throughout a period of 40 years.
Now I literally wrote about five more paragraphs, pointing out actual historical events in places like South Africa, Ancient Gaul, Rome, China, and of all Place - Poland. Ultimately - when a nation continues to grow - it expands. When a nation begins to stagnate, it holds a stable population. When a Nation or culture is dying, its birth rate begins to plummet. The average number of children born in the United States per adult woman now lies at 1.66 children. In other nations, that number is even lower. Some nations, the number is decidedly HIGHER - but those nations tend to be less industrialized. Net result is this:
Either your middle and lower class can have sufficient children for the next generation, or they do not. Tax them too heavily, and their birth rates drop. Lighten the tax burdens and the family sizes increase. Kill them off in constant warfare, and either the women must bear more children per lifetime of a woman, or the nation's population decline is all but assured. If the burden of raising children suffers from the lack of available husbands and such - the population rebounds slowly (witness European population numbers immediately after World War I and World War II).
For a somber reality: It takes 2.1 children in modern times, to maintain a zero percent population growth. Anything below that means the population is shrinking. South Korea's fertility rate is .78 children per woman. Think about that for a moment. How long will it take for South Korea's population to halve when its replacement rate is only 1/3rd that required to maintain a zero percent growth rate? More importantly, how long can South Korea hold its current national boundaries should a nearby neighbor covet their land because their population is expanding?
As I've mentioned in the past threads - what is the difference between an Imperial Citizen vs an Imperial Subject? A citizen's rights are guaranteed by the Imperium's Government directly, and can not be violated by a lesser government. A Subject on the other hand, is nominally granted a set of rights by the Imperium, but whose rights can be modified or violated by the local government in contradiction to those enumerated rights enjoyed by Citizens.
In the end? I hope that the originator of this thread can agree that there is nothing insulting about "Yanks in Space" any more than someone from England would think there is anything wrong with "Brits in Space". The fun comes in to play when a Yank portrays a Brit incorrectly (or vice versa) out of - well, ignorance of that which the other is not intimately aware of. If someone says that the Third Imperium is "Romans in Space" then that' shorthand for "take a look at Roman society and try to extrapolate what it would be like if Roman culture had had space travel.