It is, your just not gonna find pickpockets in rural places and most people don't leave their county, let alone state so people are clueless how the world at large works. Go to any big city and you'll find pick pockets at work. Further to that, many of their tourist places are far apart and remote so less likely to find them in the same kind of places as Europe, which draws large volumes of people reliably to the sames places from all over the world.
I grew up in New York City and now live in Boston and I've never encountered a pickpocket. I've been mugged three times and had a mentally unbalanced homeless guy punch me in the face unprovoked, but I've never been pickpocketed.
Do you hang around in large crowded tourist spots a lot? Crowded subways? Because that's where they are, not walking down main St. Go to times square during any major event and they are out there, but as others commented, not at the levels you'll see in European countries. Why, who knows? Tactics change over the years, they've probably found more profitable avenues of theft in the USA, God knows it is rampant.
Yeah, I rode the Subway and T for years during rush hour, I used to work in Times Square, and I've of course been to tourist events in that time. In nearly 40 years of city living, I don't know anyone who's had their pocket picked, either in busy areas or, "Main st."
While you will find pickpockets in major tourist spots in the US, they are not nearly as common as elsewhere. Here we just prefer the good ol' stick-up.