Where do your numbers come from? If you do the math, you'll find that a human being at one mile distance will be slightly smaller than the 20/20 line of letters on the eye chart. That's the fourth-smallest line. (If he were 2.3 meters tall he'd be exactly as tall as one of those letters.) By the time he gets to 200 yards he's three times as big as the biggest 'E' on the chart. If you can't already resolve hostiles as humanoids at 200 yards there is something very wrong with your vision.
Does that mean you'll always recognize hostiles at 200 yards outdoors? Of course not. They might not be wearing uniforms; they could be in disguise as merchants; they could be hidden under logs; they could be camouflaged within the woods; they could be invisible Onis. But under standard circumstances, you'll see them way before then. The DMG's general guidelines of 1-2 miles are very sensible.
Any adventurer who doesn't pack a longbow/crossbow is just asking to become dogfood to whoever does.
I am just going by what I think I could see, and I have 20/20 vision. I may be wrong, because I am just guessing, but I don't think I could make out details like that at a mile. Perhaps you could explain your calculations.