Rider Passes Yellow Line, Crashes Badly [Video]
Dangers may come from roads narrowing, blind turns, hill tops with no visibility, or lateral roads. Ignoring this passing interdiction results in fees and license suspension in most countries, simply because of the danger road users put themselves and their fellows in.
Here's a very good proof of hos bad can things go: the rider tries to pass the second car, ignoring the fact that he's entering in a restricted sector and incapable of telling whether the third car will steer left or not, maybe not even being aware of its presence.
The result is easy to foresee, as the third car steers left, indeed and the bike misses crashing extremely violently in it by mere inches, though crashing off the road meters away. This crash could have been easily avoided if the rider had just pulled back in his lane in time...