Take a look at the following screen grab from Google Maps. What London underground stations do you see?
Subway, or "Tube" stations are marked with a red circle and a deep blue bar across. The map above shows plenty of them: Royal Oak, Bayswater, etc.
The Paddington Station is not one of them. Instead the symbol for national rail service is used. From the map alone, one can draw two conclusions: 1. there is no subway station at Paddington, 2. there is only a rail station there.
Now let's zoom in the map by one level:
Now we see there is indeed a Paddington subway station!
Is Paddington a "lesser" station? Quite on the contrary, it is one of the busier hubs in London as it is linked to a rail station that runs an express train service to the London Heathrow Airport.
For a moment, let's play along and assume that Paddington is indeed a lesser location, and that one should stick to the more "important" stations. Let's explore the map while staying at the zoom level where Paddington Underground is visible.
Panning a bit northeast there is Marylebone railroad station. There doesn't seem to be a subway station nearby:
What if there is a subway station at Marylebone, even though we are already looking at a zoom level that shows Paddington, the "lesser" station?
One more zoom:
Nope. I suppose there is no Tube at Marylebone after all.
Not so fast! Just one more zoom:
Gee, not only there is a Marylebone station, it's a damn convenient one - it connects right to a rail station! Well, just to be fair, most rail stations in London are linked to subway locations, but this is definitely not the impression an outsider would form by staring at this map.
One can argue that this is a usability issue, or even simply, a "data problem". But it nevertheless shows the oversight of presenting accurate information. Ask Google Maps "where is the Paddington Station", it will show you the rail station. Is there a subway station that's nearby? One looks at the map and doesn't see a Paddington Tube, drawing the wrong conclusion.
Leaving information out can be harmful in two ways. One is that it interferes the formation of totality: "What are the seasons on earth?" asks the martian. "Winter, spring, and summer", answers the earthling. "So you don't have autumn?" "Oh yes we do, and it is called the Fall in some places."
Also it forms the misconception of hierarchy and classes. As we can see, as far as urban planning goes, all London subway stations are created equal. Some might deserve more light, but the two worthy examples we looked at are somehow swept under a rug.
I hope Google addresses this problem soon, although I'm not holding my breath. Meanwhile, let's extract a rule of thumb to guide our future software designs:
"the fair representation of information in totality"