Some of the observations are amusing, some poignant, and a few quite condescending. Some provide us with some of those “Gee, I never really noticed that before” moments. Some are valid and some are totally friggin' clueless. In other words, they aren't much different from our own observations about ourselves.
Some of my favorites:
I was startled to find out that "God Save the Queen" has alternate lyrics.There are literally hundreds of observations about American quirks, many which caught me off guard even though I've spent quite a bit of time in Europe. Many are amusing. Some are offensive (that might show the observer's prejudice). Nonetheless, the list is quite informative.
The fact that so much American cheese is coloured orange surprised me. ( Orange cheese is most likely a cheese-like product and not actually cheese. - ed.)
People using checks is antiquated in terms of other developed countries.
Everyone eats with one hand and keeps the other hand on their lap all through the meal. Also, sometimes they go through an elaborate switch-fork-to-left-hand-pick-up-knife-in-right-cut-up-food-then-switch-fork-back-to-right-hand dance.
Leave your money in the mailbox. You drive onto a persons home property and they are selling something (small bundles of fire wood, home grown produce, or home made Adirondack chairs) and a sign tells you "If no one is home just leave the money in the mail box."
That they probably have the best customer service culture in the world, but can rapidly descend into being the most aggressive if challenged.
One language - I noticed in Europe most people speak more than one language and usually even 3 or more ( Who needs to speak more than one language in a place like Kansas or Idaho or Ohio? Here in northern New England a large number of people speak French due to our proximity to Quebec. In the Southwest it's Spanish, Navajo, Hopi, or Zuni. In Florida it's Spanish. In the Dakotas it's Lakota. In Europe you might cross through more than one country in a single day. In the US you might be able to make it across a single county in a day. Scale is everything. - ed.)
My girl friends from Ireland and the UK find it strange that the bathroom stalls have such wide gaps between the wall and door. I never noticed it until they talked about how bizarre it was. To this day, my only guess for why is that maybe it's so that you can tell a stall is occupied. Hmmmm.
American lemonade is brilliant stuff. In the UK if you ask for lemonade you get Sprite. Bleh. In the US you get something close to proper cloudy lemonade.
American drivers are far more likely to stop and let a pedestrian cross the road, even when there is no marked crossing. Possibly due to the novelty of seeing someone on foot.
I was shocked to find that hired help is not the norm in such a wealthy nation. When I was a kid I thought all Americans had a butler, a housemaid and a cook.
There is a huge culture of self-help / self-improvement.
My Spanish friend was amazed at all the houses made out of wood in New England.
Checkout clerks in the grocery store do their work standing, not sitting.
Americans waiting in line is just preternatural! Recently, waiting for a bus from DC to Philly, there was no waiting area or anything foreseen (one of those bus companies that doesn't use stations). It was Friday night and the buses were all booked solid. Tons of people were showing up, and yet everyone was till queuing up perfectly politely, waiting their turn, inquiring where the line started and how far it stretched back. It gave one faith in the waiting process, brought the stress of the situation way way down.
The pervasiveness of religion. Europeans know that Americans are religious, but you don't get a sense for how pervasive it is. Everyone mentions God all the time like it ain't no thing. People would lose their jobs over that in France!
The thing I've seen non-Americans struggle over the most is the scope of influence of local government. Our local (state, and even city or other municipality) governments have a lot of power and influence over day to day life, so there's no one standard for how US law enforcement, zoning, city planning and traffic management, utilities, animal control, and public works are run. Liquor laws, trash pickup, and even criminal laws might seem just as bizarre and foreign to someone from the next state or city over as they are to someone living halfway across the world.
Buy a coffee, have it endlessly refilled for no money. This is like magic heaven stuff to Brits. (I can attest to this. My British ex-fiancee thought it was a wonderful thing every time she was here and made the best of it. - ed.)