Wooden houses--in many countries the common material for building houses is concrete blocks. Older houses might be stone or brick.
I've mentioned that I hang out on a travel board. I'd say that the biggest surprises for visitors and potential visitors have to do with transport. People are very surprised that there are so many famous places that you can't get to by without a car or a tour. Yellowstone, Death Valley, Big Sur, for instance. People are also surprised to discover that there is only one passenger train company and one major long-distance bus company.
Car buying. Australians seem to be the most surprised at how hard it can be to buy a car. In the US, laws are set by the individual states, but Registration includes some insurance. So, in Australia there is a traveler's market in used cars. You just buy one from someone who is finishing a trip, take care of minor paperwork and you are on your way. In the US, each time a car changes hands, it must be registered anew. You have to produce an address in the state where you want to register it. Some states require you to prove you live there, say, with an electric bill in your name. Some states have ID requirements that are impossible for most non-residents to fulfill. Then there's having to get the mandatory insurance.
Camping. In the US, camping is seen as a way to experience nature, so most campgrounds are out in the wilderness. In many countries, camping is an inexpensive lodging alternative. Campgrounds are located in or near cities, with convenient public transit. They may have cafes, laundries & other amenities. People are surprised that they cannot visit a large city, stay in a campground, and use transit to get around.
People are also surprised to find that it is hard ot find campervans for rent, as opposed to larger RVs, and that a rental car + a cheap motel may be less expensive.
In many countries, "Wild" or "free" camping is allowed or at least tolerated. That's were you pull over at a likely spot at the side of the road & set up for the night. As long as you are respectful and quiet, you are probably OK. In the US, you may just meet a police officer or an angry landowner. So, people are surprised that they can't save money by renting that campervan and doing wild camping.
Distances, yes. We once had someone planning to drive from Chicago to the Grand Canyon in one day.
That American B&Bs are usually luxury lodging, often in restored old homes furnished with antiques. Not some rooms with shared bath in a home or small hotel, often described as "cheap and cheerful."
Edited to add: a visitor from Brazil wondered if the high number of wooden buildings was the reason there were so many fires. Every day in Los Angeles, he saw fire trucks racing somewhere. He was surprised to find that the Fire Dept responded to everything--fires, medical emergencies, traffic accidents, hazardous waste spills… (My local FD recently released a report showing that something like 80% of calls were medical.)