So I'm reading the news and it says, "Three Americans have been found dead at one resort". Why is it "have been" and not were?
While reporting news, "have been" is generally preferred to "were". One of the reasons for this is to indicate that this event happened in the recent past.
It is possible to use "were" but then you would add a time in the recent past when they were found, like "this morning" or "at 2 o'clock", for example. Present perfect also emphasizes the effect the discovery has on the present.
I'm assuming the bodies were found at different times, since a present perfect tense suggests a continuity of action in the past, whereas a simple past tense describes an event that occurred and ended at a particular time.
Or perhaps it is just the writer being superfluous.