Your suspicions that drivers in Italy do several things quite different than in the USA is absolutely correct. I drove in southern Italy, near Brindisi, in 1972-73. Initially I was terrified by road conditions and Italian driving habits for about half a year. Slowly I began to understand that the unwritten Italian “Rules of the Road” were very different than in the USA. Here's what I can remember about those Rules.
Drive fast and know how to handle your car (includes steering and braking) at high speed on often poor roads.
Learn how to look for what other drivers are doing or are about to do. If you accelerate, your front bumper raises a bit, and if you brake, your front bumper drops down a bit. There is an Italian phrase which translates as “Always keep your front bumper up!” This is both a joke and a standard practice on Italian roads. Similar to the change in front bumper position as an acceleration indicator, a car’s front wheels can indicate, a moment before an actual lane change, that a driver is initiating a steering change.
In the USA a smart driver will eventually learn these things, but most drivers are unaware of them. Compared to Italian drivers, they act passively, like sheep in a herd. Americans often drive distracted without observing whats going on around them. In Italy knowing whats going on and how to respond are mandatory for survival. Compared to typical American drivers, Italians are very observant and they expect other drivers on the road to be the same.
Learn how to signal other drivers both with your horn and your headlights. This is actually very useful. Unlike in America, it is not considered rude.
Know exactly how wide your car is. In towns and cities you absolutely will be in situations where you can fit in narrow spaces with an inch or two to spare. It took me months to know, with confidence, where I could fit my car.
On multi-lane roads, such as the AutoStrada, you must pass only on the left, and you must use turn signals during the entire pass until you return to the right hand lane.
In the US, most drivers are rather passive or timid about passing slower cars. They usually follow a slower car for a while, often tail gating, until they reach a stretch of road that allows passing. This standard US behavior pisses off Italian drivers. On Italian roads there is a pecking order (an aristocracy if you will) based on the expense of your car. A more expensive or powerful car is supposed to pass a cheaper car without hesitating. A car lower on the pecking order must yield to the superior car overtaking it. On narrower two lane roads, this meant the slower car partially pulled over to the right giving the faster car more room to pass. I found that if I followed for a while before passing an inferior car, my unwitting violation of the Italian Rules of the Road insulted the driver of the slower car to the point that he moved his car to the left instead of to the right as I passed him. I clearly remember my surprise when I decided not to slow down and follow before passing. The other driver readily cooperated with me by moving to the right! This was not unique to that one driver – I found it was easily repeated with others.
My experience was a long time ago, but somehow, I don’t think things have changed too much in Italy.
