Several things, but top of the list is guns.

Police officer: *sees black man running*
*spins wheel*
dadada·da·da-da-da–da–da—da — da TRESPASSING
(The wheel is 60% trespassing)

Also, what are sheriffs for?

Tipping and calculating your own taxes

Cars. You seem to buy cars like smartphones( actualy probably even worse since buying phone on credit dosent seem to be as common nowadays ) . If you can afford the credit payment for the card dosent mean you can afford the car. In fact why everyone buys stuff on credit cards in the US . It seems insane to me to go to debt for a stupid cofee.

Putting american flags everywhere. What do you want to tell me with that? That you like the country? Obviously you do or else you wouldn't live there

Everything in this thread so far is normal stuff I could have guessed. Guns, metric, tipping, etc. Most of it has large groups of people in the country that agree, or at least know.

What are some non-obvious things? Culture shock isn't about major political issues. It's about universal things that turn out to not be universal.

For example, US people have a strong culture of how standing in line works. It's basically a moral sin to butt in line unless you have someone holding your place. This is universal in the country. My understanding is that other countries differ. Is that true?

Pickup trucks everywhere. No public transportation usually. General Tso's chicken is a typical Chinese food you get. Weed products are available almost everywhere legally. Light beer. No proper lager beer even in small breweries. How people drive. No sidewalks most of the time. The whole health industry. Electric sockets. So many churches. The general war against trans people. The general war against women.

What's up with that "bus shaming"? It would never occur to me to judge people based on whether they use public transport VS own a car!

School/mass shootings.

Sandwich for lunch.

Gas operated dryers.

High school proms being such a big thing.

Garbage disposable units.

Americans seem very "fighty" compared to people from many other countries. You just have to say something that could be construed as liberal (the American kind) or conservative, too politically correct or incorrect, or mention you ride a bicycle or have an outdoor cat, to set some people off. With some Americans having a conversation is like navigating a minefield, especially those who have very little understanding of the rest of the world and reads everything you say into an American context, language barriers and all.

I love talking politics, and have had pleasant conversations with all kinds of people but I have learned from experience to just not bother with Americans, unless they're the very curious and open kind.

Worshipping guns.

Work hard.

Why???