The Star Trek universe seems pretty nice - an Earth without greed or war, and a mostly Anglo-European command system. Wait, what?
Yeah, Star Trek's Earth is a world where most of the continents were nuked to ash, and what was left as the majority was European and American populations. We already know that humanity went through several major wars prior to the Federation or even Starfleet being formed.
Star Trek fans were given a special delight when, in 1987, Star Trek: The Next Generation launched. Arguably the best Star Trek spin-off show, TNG had a humble and dignified approach to most episodes, especially when comparing to Voyager.
The first episode, Encounter at Far Point Station, gave an insight in to the past of the Federation and humanity which had pretty much been a mystery in TOS, which hinted towards the past but never really dug deeper. Q points out that humanity engaged in a long struggle with itself; drugs and degeneration pretty much hit most of the world; it was a link in with TOS episode Bread and Circuses which showed a not-so-sunny near future for its audiences (with terrorists killing millions with nuclear weapons.
Memory Alpha (the most accurate wiki for Star Trek material) states:
"various parts of Earth were still affected by what became known as the "post-atomic horror." In 2079, one such culture reverted to a state of near-barbarism that followed the credo "[Kill] all the lawyers," and "[Guilty] until proven innocent." (TNG: "Encounter at Farpoint") Due to these and other factors, parts of Earth continued to be in – as Captain Jean-Luc Picard put it in 2365 – "chaos" well into the early 22nd century. (TNG: "Up The Long Ladder")"
We admire the Earth of the Star Trek universe for ridding many of the socio-economic matters we suffer today such as poverty, inequality and racism.
From Memory Alpha:
The post-atomic horror gave way to the stirrings of new attempts at establishing various unified world alliances, including the European Hegemony in 2123. (TNG: "Up The Long Ladder") These alliances were eventually instrumental in the establishment of the United Earth Government in 2150. (TNG: "Attached")
"By the early 2100s – less than two generations of the post-atomic horror – humanity was finally able to eliminate most if not all poverty, disease, war and hunger. Along with it, a lot of other things disappeared from humanity, including hopelessness, despair, and cruelty. (TNG: "Time's Arrow, Part II"; Star Trek: First Contact; ENT: "Broken Bow")"
How did this occur? How did humanity manage to get rid of such social diseases?
The majority of the populace outside of Europe and America died. Oh, and genocide was a popular method of ensuring the best stock for humanity.
This is where real world dynamics will bridge with the show:
Memory Alpha reports that 600million were directly killed due to Nuclear Strikes of World War Three.
Then the post-atomic horror "Earth historians to refer to the global turmoil which resulted after the end of the Third World War in 2053. Because the war was a nuclear exchange, large populations of Humans were bombed out of existence, and the survivors were placed in jeopardy by radioactivity, "
Back then, countries such as China weren't the same powerhouse as they are today, so take in to consideration that chances are that China would be one of the first to be hit during a Nuclear war, say 40% of the population was killed in China, that's nearly 600million additional people, bringing the death toll much higher than the show indicates.
Then the nuclear winters - the Johnston Archives has a good article relating to this - would leave about 60% of the population in total completely devastated.
Africa would become a wasteland; it already suffers from low water supplies and millions of deaths from starvation - imagine a nuclear fall out situation where the atmosphere's temperature would rise even higher.
Regions such as the Middle East and Southern Asia would have the same problem.
Why would Europe and America survive above all else? The climate in these continents are mild, and thus an increase in temperature would be more adaptable than else where.
Future generations would struggle to repopulate with radioactive-related deformities and retardation killing many potential generations.
Look at the senior staff from the primary television ships and tally their ethnicity:
Picard - French
Janeway - American
Sisko - American
Arthur - American
Kirk - American
Riker - American
Spock - Vulcan/American
Chakotay - American
Cara - Bajoran
Ta'pol - Vulcan
Crusher - American/Scottish
Bones - American
Flox - Alien
Bashir - American/English (?)
The Doctor - Hologram
Now, yes they are actors and their characters reflect that, however in the universe it is seemingly mostly European and Americans who are populating the human ships of the federation.
Star Trek has now taught us that we need to wipe out most of the human race, make contact with space elves and generation blast the shit out of anything that is a threat - great diversity and morals, eh?