I have lived in the US for about 17 years and spent another two summers here before. By now, I am quite used to all the comforts and quirks of American life.
But there were many things, good and bad, I had never seen before I came here. I don't believe all of them had just been invented right before my arrival, especially since I often encountered the what-are-you-an-idiot facial expression when I asked someone what something was.
Indeed, Americans often don't realize how good they have it. This often shows in movies and TV shows which show some "ordinary" things in presumably foreign settings.
I have probably forgotten how many of the things I had not seen before, but here are at least some of them:
A mop. Believe it or not, my fellow Americans, where I come from we cleaned our floors by getting down on our knees and using a heavy rag.
A baseball hat. Or, for that matter, a baseball bat, a baseball mitt, a baseball stadium, or just a plain baseball itself.
A football. Where I come from a football is round, i.e., what Americans call soccer.
A fire lane. Or, for that matter, a fire escape and fire stairs. My first impression of America was that they must have lots of fires here since they take so many precautions against them.
Minimum drinking age. As a teen I used to spend my vacations in a Carpathian castle. It was unthinkable that I wouldn't have a drink on New Year's eve or some other occasions. The bartender would not hesitate to sell me one. Did my father know? Of course he did. He paid for it.
An air conditioner. I have, on rare occasions, experienced air conditioning, but never saw an actual air conditioner.
Diet cola. I certainly drank a lot of cola before, but never even dreamed about the sugar-free variety. When I visited home ten years ago and asked for Diet Pepsi, they had no idea what I was talking about. Of course, they did have Pepsi.
A wooden house. I am not talking about a log cabin. I am talking about a regular family house. Where I come from, they are built from bricks. When I first learned American houses are built from wood, I thought I finally understood why the fear of fire.
A waiter who did not have to go to waiting school. Where I come from, waiters are respected professionals who spend several years going to school before they are allowed to wait on people. They often wear black tuxedos, or at least black suits. They are very formal, never kid with customers, and things like that.
When I visited home ten years ago and talked to a waiter in a casual way (as I got used to in America), he handled that very professionally. I didn't do it again.
Total strangers calling me by first name. Well, it did happen, but only when I was a child. But not as an adult. Only after you have become really close to someone, you formally agree to call each other by first name, and then you do. There are a few exceptions: Students, for example, call their fellow students by first name, and continue to do so even after they have graduated. On the other hands, colleagues at work must first agree to call each other by first name.
Total strangers starting a casual conversation. Unthinkable where I come from. Quite common in America.
Quarter pound of meat on a dinner plate. Even in the classiest restaurants in my home we only eat what we need. In America everything is bigger, that includes dinner portions.
Doggie bag. This has probably to do with the above. Since restaurant portions are reasonable, you either eat it all, or leave it on the plate. You don't take it home with you.
Eating with a fork without a knife. To this day, I don't understand how Americans can do it. They cut their food with the side of their fork and it does not fly all over the plate (let alone all over the place). If they do use a knife, they cut a bite off, put the knife down, transfer the fork to their right hand, and eat. We used to (and I still do) hold the knife in the right hand, the fork in the left hand all the time. We not only use the knife for cutting. We also use it to slide food onto the fork. We put the fork in the mouth with the left hand. Doesn't matter whether you're right-handed or left-handed.
Auto-flushing urinals. In many places in America public urinals flush automatically after being used. Where I come from, you flush it yourself, and you never forget to.
There's probably a lot more, but, as I said, I got since spoiled and don't quite remember it all.