Because that's how it is shown in films. There are just fewer abusive translations. The norms of society and all that. In real life, the more cultured a person is, he will cover with those obscenities more tricky. It doesn't really depend on nationality. :-)
where does "oh my God!" But what about "oh, fuck !!!" ? In my opinion, this is more commonly used, although of course I could be wrong. Not all Americans are religious. But religious people can also use "Holly shit" :)
And Russians swear, and not Russians. As Maxim said, we have slightly different obscene vocabulary, but at the same time, as a Russian can be surprised with the words "Lord", "Oh God" and so on, so an American can, in surprise, shout "fakin hell" ("fucking hell"), and a German will say "Scheisse" ("shit"). It seems to me that everything depends on a specific person and on a specific situation.
I am a Russian person, but I am surprised and cursed with the words "holy hedgehogs!", "crumple my tail!" or "fluffy cat ass!" I don't think it will spoil your statistics very much, but I disagree with the fact that every Russian swears from emotions.
Interesting question. We have a mat associated with genitals and sex. These are forbidden words that do not pass censorship on TV. For Americans, foul language is more often associated with an insult to faith. Even "chizes Christ" (Jesus Christ) is translated into Russian as "damn it." "Holy Shield" (holy shit) - like "damn it". In short, sacrilege flourishes in our country (devil, devil), and in them - obscene language (all kinds of "fak", "fakin", etc.)