I'm sure L4 will back me upon this (as he has far greater real world experience than me) but:
a) Traditional DPM (disruptive pattern Material) Camo works well if you're stationary but is often worse than a plan muted olive green or khaki if you move. So it tends to be use in ambush and surprise for maximum effect
b) Different sorts of camo have different effects. Making you look a bit different, but still in plain sight, can sometimes give just enough extra time for the 'camo' target to get a shot in first, or disrupt a firer's aim to enable an advantage: Classically, battleships painted in Dazzle patterns don't hide a vast ship, but, by breaking up the silhouette, they can lead an opponent to miss-judge range, speed or even direction (and – if you start painting out funnels – even type) and that can all give vital seconds to fight or flight.
That top shot is an excellent example of two things: not only is it very hard to see the outline of the 'shooters' but I actually find it hard to even concentrate on the picture at all. While I'm squinting and puzzling, that might be just the time they need to get off a round with their nerf guns
!
Mind you, if they swapped places with the chap on the sofa, they'd probably be sitting ducks
John T