The right colours on a model really show it up as well as possible. Each to their own, I know, but personally I think there's nothing worse than an excellent model painted wrongly.
But on your layout it's not just the attention given to getting liveries and weathering right, it's the whole atmosphere it recreates. Looking at those pictures, I can almost imagine the smell of turf smoke from the cottage next door, and the coal smoke and hot oil smell from the engine..... the attention to all details is great, down to the puddles on the ground.