I know this was mentioned in another thread, but for the life of me I couldn't find it.
While checking up on Starship Troopers I came across this bit of information regarding telling people and showing them; and when showing them, how difficult it can be for them to make up their own mind, and get the message the author intended.
"...on the dvd commentary, Verhoeven explains that the final scene was primarily intended as a very cynical coda: it shows that Johnny Rico has become a full-blown mindless war machine just like Lt. Rasczak (he has even copied his war cry "Come on, you apes, you wanna live forever?") and that mankind still thinks they can win this war through superior firepower. In this context, the final tag line 'They'll keep on fighting' can be read as 'They still haven't learned anything'. Verhoeven admits that many viewers and critics entirely missed this subtext of the movie, and misinterpreted the final scene as a statement of militarism, or a simple allusion to a sequel."
Because an author knows where they are going with the story and what their intention in writing it is, what appears to them as an obvious hint(s) to lead the reader to the right conclusion may not be nearly as obvious to the reader who doesn't know what the author intends with the story, or from what they have read so far has come to a different idea about where the story is going/what it's about to what the author intended.