I worked as a barista for awhile at a locally-owned/operated chocolate and coffee chain in midwest America. Starbucks is the main competitor in that area. It wasn't Coffee of Doom, but it was fairly hipster for the midwest. Beans were locally roasted, etc.
Single/double/triple/quad refers to number of shots pulled. Without a size specified, a single is a small, a double is a medium, a triple is a large, a quad is a large with an extra shot. Generally.
Starbucks-ese also has cup sizes (fluid oz) for tall, medium, and venti. In normal sizes that would be small, medium, large. Specifying a cup size means x shots in that cup size.
Starbucks-ese bastardizes the actual meaning of 'macchiato'. Their version of a macchiato is baaaasically a latte. So what isn't shots in the cup, is milk or syrup.
A latte is a third espresso, a third steamed milk and a third foam. Americans also add syrup. A Starbucks caramel macchiato upside down would just have the coffee floating on top instead of at the bottom.
An actual macchiato is espresso with a dollop of foamed milk. An actual dollop. Of the foam. Doing this upside down would be really stupid.
Yes, Americans put caramel syrup in their coffee. They also put 50 other flavors of syrup in their coffee. Some Americans choose to drink coffee straight or without syrups. However, Americans are very unlikely to do this at Starbucks.
This is in part because Starbucks uses cheap beans and to compensate for the cheap beans, they tend to over-roast their coffee beans, leading a burnt taste. Starbucks coffee tends to be difficult to drink straight. I believe Folgers, the leading brew at home coffee company, also does this, but it's been awhile since I've thought about it.
Americans are not the only ones who put sweeteners in their coffee, but a regular cup of American joe is probably brewed a lot more weakly than European variants. The regulars who weren't American would have straight espresso, black coffee or cappuccinos. I got pretty good at making cappuccinos over time. I was told once by a regular couple that 'in Europe, they didn't need to provide free refills-- one cup of coffee was always enough'. American diners are all about the free refills.
Vietnamese coffee is also very sweet, due to using sweetened condensed milk as part of the recipe.
The more you know. Insert star rainbow here.