Top bird artists not so good!!

Had this interesting one pointed out to me . . . virtually all the top field guide artists seem to get this wrong . . . .

Look at the size of the bill on any bird in the family Paridae . . .
Black-capped Chickadee http://davesgarden.com/guides/birdfiles/showimage/229/
Carolina Chickadee http://davesgarden.com/guides/birdfiles/showimage/2413/
Chestnut-backed Chickadee http://davesgarden.com/guides/birdfiles/showimage/2383/
Coal Tit http://davesgarden.com/guides/birdfiles/showimage/646/
Blue Tit http://davesgarden.com/guides/birdfiles/showimage/981/
Great Tit http://davesgarden.com/guides/birdfiles/showimage/826/
Cinereous Tit http://davesgarden.com/guides/birdfiles/showimage/1117/
Tufted Titmouse http://davesgarden.com/guides/birdfiles/showimage/326/
Oak Titmouse http://davesgarden.com/guides/birdfiles/showimage/633/

all have quite chunky bills nearly a third of the length of the rest of their heads

Now look at the tiny little bills shown in the field guides . . . National Geographic guide seems to be the worst, but Collins (UK) and Sibley (US) are almost as bad

Why do they all get it wrong, I wonder??

Resin

PS as an aside, we don't appear to have any Mountain Chickadee photos on BirdFiles yet - can anyone add some at http://davesgarden.com/guides/birdfiles/go/470/ please?

Just one reason among many why I am hoping to get a guide with photos.I just don't always find the drawings looking like the bird that I saw!

Great heads up on this Resin, I'm making a note in my Sibley's.
As an aside, I sure wish I had seen and/or photographed a Mountain Chickadee. I'll be keeping a look out especially when I visit the nearby mountains.