I'm new to the forum and this is my first post, couldn't resist chiming in on an Italian vs American coffee discussion!
I'm Italian and have been raised in northern Italy by a southern Italian family. I have been living in the USA for 2 years now, and have visited my local NJ family plenty of times before, so I have a good view of the differences between American and Italian coffee. Finally, I had basic training as a barista, so I can speak with some professional knowledge.
another_jim basically nailed it: Italian coffee standard (i.e. certified Italian coffee) uses an average of 7 grams (+/- 0.5g) per dose. The overwhelming standard in Italian coffee shops (we call them "bar", as opposed to "pub" and "cocktail bar"), is to use a ~14g dose and pull two shots, even if the order was for just one.
Coffee shops can easily serve 500 shots per hour at peak times, so the second shots is quickly used or just discarded. The reason is that the single shot basket is perceived to be more difficult to use given that calibration is done for the double basket, plus it is usually reserved for decaf as it is less commonly requested.
Practically nobody uses larger baskets, the 15g basket is the de-facto standard. Consider that ordering a "doppio" (double) costs exactly double the price, people usually don't do that
Cappuccino and macchiato are very common choices in the morning, while in the afternoon it's rare to drink a cappuccino, while a macchiato is somewhat common. Italians tend not to drink milk after lunch, it's sort of an unwritten societal rule.
From a taste profile, there is no "Italian" coffee. Anyone who traveled Italy extensively would have noticed that every city is a country on its own, and so is coffee. I was raised close to Milan, and the local preference appears to be for sweet 100% arabica blends, while travelling south would shift the preference to robusta / arabica blends.
When compared to American coffee, the "Italian" coffee is always less bitter and astringent, even when drinking robusta / arabica blends. An Italian is almost never satisfied by foreign coffee, as the roast is usually darker abroad, and the blends tend to be a bit more woody or strong. I must say, from personal experience and preference, that Amsterdam was the only place I visited where local coffee blends were very good for my taste.
Nuna was also mostly right: Italians do drink coffee fast most of times, because the majority would drink it before going to work (while already late
) or during a break. Coffee shops that can serve an espresso within 2 minutes from order would naturally attract more people. The only time when you can relax a bit more is on the weekend, while strolling in the city center and taking the time to sip.
When it comes to brew ratios, a barista is typically pulling 1ml/s. A certified Italian coffee is 25ml, a ristretto is usually cut short so it ends up being 20-25ml (altering the flavor profile) and a lungo is kept going for longer ending up being 25-30ml (altering the flavor profile). You should note that the preparation in terms of coffee quantity wouldn't change, it's always ~14g.
Water filters are practically always used, but there might be variations. I know Naples takes pride in their water, so some bars might opt for the local tap water, but in practice when you open a bar and select a blend, you would always test the water and most of times you would be recommended to use a water filter. Without it, machine maintenance is much more expensive, so it is a question of economics, not really taste profile.
I also need to dispel a myth about the fact that Italian coffee is always good wherever you have it in Italy. Unfortunately, an Italian knows that most coffee shops can't make good coffee and most restaurants can't as well. There are simply so many coffee shops that finding a decent / good one is easy. The reason behind this comes from the business: coffee shops usually cater to the business crowd, serving breakfast in the form of croissant and pastry, together with coffee, then serving a simple lunch and possibly aperitivo / happy hour (food + drink). Coffee is not the sole focus of a coffee shop, as strange as it sounds. Training for the staff is simple and focuses on maintenance and operation of the machine, rather than taste. Tamping lightly is definitively common, but not the rule and I would argue that most times that's an indication of bad preparation (exceptions apply!).
Third wave coffee is taking some roots in Milan, but it's definitively not very common. Historical coffee shops that care about flavor and preparation exist in every city, and the quality and taste you get from them is night and day compared to the business-crowd-focused coffee shop, so take this in consideration.
Finally, Italian coffee shops history is complex. While machines were certainly a work of art and craftsmanship, the coffee they produced for the first few decades wouldn't taste very good for current standards
Sorry for the long post, I am more than happy to answer any curiosity people might have. Remember: whatever I said above is anecdotal, Italy is a very diverse country with many local variations. What rings true to an Italian from Milan would sound alien to an Italian from Naples.