Futbol and Nations' Colors

I've been for a long time about "national colors." Because it seems, especially in colonial countries, that the colors of the nation in sport and identity have nothing to do with their flag. Now, here in the US, we expect our national teams to have some combination of red, white, and blue. That's the flag. But it's astounding how that doesn't work elsewhere in many occasions. Let's start with the obvious--the British Commonweath. Here, I get it. When you get the Union Jack jammed down your throats, you look for something your own. That's why even though their flags have red, white, and blue, Austrailia is known by its green and yellow, New Zealand is known by its all black, England is known by its all white and sometimes red, and Scotland is known by its blue. But other countries are a mystery. Italy has three colors in its flag--red, white, and green. So why are their national team identified by the blue and white ? Brazil's flag is mostly green, yet their teams are known by blue and gold. The Dutch, thugs that they seem to have become, have always been orange, even though there is no orange in their flag. And most countries have many variations, depending on who they are playing, to avoid confusion as to whom they are playing. But I've never seen the German team in anything but white and black. It's just....odd.