OK, try parsing these:
The room is misty but characters looking south can see a dim shape, possibly a statue.
The room is misty but characters looking south may see a dim shape, possibly a statue.
"Can" implies certainty - you look, you can see it. "May" implies uncertainty - you look, you may or may not see it; which is what I'm after.
And even then, "can" in the first instance above should be replaced by "will" to make it even more clear.
Lan-"is 'can' the new four-letter word in design?"-efan
Except "can" does not imply certainty. There isn't much of the horse left to beat, but saying that a rectangle can be a square does not imply that all rectangles are squares.
IMHO, if you have this much of an issue with parsing the word "can" you are over-thinking it. The text in the PHB is not meant to be read like a legal document.
From a logic perspective (ignoring the rules for a moment) I agree that if someone makes enough sound and they are close enough you may know their position.
But I don't care if you're blowing a bugle, if you are 100 yards away if I can't see you I won't know your exact position. I may know your approximate location, and in most circumstances I will know your direction.
Imagine another scenario. You're alone and blindfolded in a gymnasium. Someone enters the gymnasium. You may have a decent idea of where they are by hearing a door open and hearing footsteps. But now assume there's a basketball game. Odds of hearing someone over the noise unless they're really close is minimal. Add a cheering crowd, or make it an open basketball court in the middle of a noisy city? Not gonna happen.
As far as the rules, I don't see an explicit rule that states that the game would not work the same as the real world. Rectangles aren't always squares simply because rectangles can be squares and you don't always detect someone's location simply because they can be detected based on noise they make.