Why do Americans say "shit" so often ?

I’m guessing it’s this.

Shit’s a great, all-purpose, word. You can add as many syllables as you need to cover almost any situation. If you’re feeling relaxed, you can elide the t sound. OTOH, you can always hit the t sound hard if you’re feeling irate.

All in all, I’m not inclined to take much nonsense from a Limey while the Shyte Brook still graces your landscape.

Now fuck, on the other hand … Fuck is a much funnier word than shit, of course. Fuck has the advantage of being a K word, and rhyming with Duck, so naturally, it’s the word or choice when feeling fiotous. Also, fuck works better as a gerund, so it’s situationally more entertaining.

Bloody if I know.

I’ve no trouble with most swear words, myself; it’s the intent that matters.

And yet, there you go using it!

Don’t let the rest of the world know, but every single American teaches their young to say “shit” as their first word.