FFS I always thought like this! Why are aliens always fucking united? If aliens exist, they're definitely going to have countries and cultures and languages etc.
Well typically the idea is that in order for a civilization to advance as hugely as an alien civilization that can preform intergalactic travel is one that had to have become a unified people, as evidenced by humans we tend to excel on our own and in competition but if a coalition of individuals worked together toward the same cause then it would work far better.
Most sci-fi material I've seen mentions universal translators at some point, and most of the good ones do have civil differences amongst the same race.
Babylon 5 had an interesting taken on this with the Drazi. In order to determine leadership, every five years they randomly and arbitrarily choose a side, green or purple, This is represented by a sash they wear. Once sides are "chosen," a massive global civil war brawl takes place, fighting over which color is better, the greens or the purples.
The procedings hold little meaning beyond tradition, but the also makes it difficult to hold a grudge because next cycle, you just might end up on the side of the other color.
I think the point in many sci-fi pieces is that aliens have achieved such a high level of technological and sociological/political advancement that they are united, unlike humans.
What's amazing about mass effect, is that almost nothing in it is original. It all is based on other sci-if stories. However, they are all twisted just enough to not be blatant rip-offs, and they put together into a melting pot of ideas that come together into a beautifully unified, completely original whole.
The procedings hold little meaning beyond tradition, but the also makes it difficult to hold a grudge because next cycle, you just might end up on the side of the other color.
Let me tell you about Homestuck :o)
What have you guys done
Now he can't be stopped