But why? The barrista at an Italian bar makes hundreds of shots a week. I have never seen a mistake. Even the espresso they pump out at the bars at the huge trade shows in tiny plastic cups always seem to be right on the mark.
I think (and this is just my own idle speculation) that it's because the average Italian won't drink crap, and most Americans will. I think the same applies to the food in Italy...even the most mediocre is usually better than the average here.
You can get a decent espresso in the US, or at least in Portland (ok, Seattle too). The Illy-trained servers where my son Joe works pull good shots, nearly every server at the Torrefazione outlets I go to do the same, and even, gasp, Starbucks, with their fully automatic machines that take the work out of the hands of the barista (the fast-food model at work), can produce a drinkable espresso most of the time (ask for a ristretto and the odds go up).
Only when we demand a good espresso will we consistently get one. But when the typical drink at a 'specialty' coffee outlet contains 12-16 oz of milk, some sort of sweetened, flavored syrup, and a topping of whipped cream, the espresso lost in there doesn't really matter.