In Italy, especially in big cities like Rome and Milan, traffic simply would be a disaster if the thousands of motorcycles and scooters didn't lane split to the front of the pack.
By doing so virtually everywhere, the room is preserved for cars and as soon as the lights turn green, the 2 wheel brigade is instantly gone.
Italians RARELY get upset driving. It's remarkable. For the most part, they remove their ego from the equation because they are just so much more pragmatic.
Asshole Americans are nothing but ego behind the wheel, and (not everyone but most of them) especially if they drive what I call the "Universal Assholemobile", some Goddamn gigantic truck which they repetitively use to deliberately intimidate other drivers by tailgating and cutting you off and other such asshole douchebag behavior.