English doesn't have a consistent default; it depends on the context. "Trees are green" is a general blanket statement, presumably applying to all trees... or to be precise, at least the vast majority. It doesn't actually entail a strict 100%. For an example where it's more obvious that it's different from using "all", "Humans have 10 fingers" doesn't mean that any being with 9 fingers is automatically not a human. It's a "general, but not universal" statement, or "almost all". Though, notably, it's more universal than "most".
On the other hand, "Teenagers did this" isn't by any means accusing all teenagers - that example uses the Spem logic. In just means some teenagers did this.
So English seemingly varies between
Japanese is a far more interesting case. Since Japanese has no word for "the", and its general philosophy is "leave out
as much as you can to infer it from context", often an unqualified noun in Japanese conveys the meaning equivalent
to "the". Although, I'm pretty sure Japanese would also express the English "
While I like the thought of