I have heard a lot of these things from South Asians.
Return Policy - Does not exist back home. Though I hear now merchants are being forced into this as so many Indians have spent time in the US.
Informality at work - Very different from over there
Tipping - Very foreign to them as it does not exist back home (earning the consternation of restaurant waitstaff)
Traffic - very orderly (or at least we don’t have daily 15 car pileups that generally involve an elephant or a camel)
One thing that stuns by Brit in-laws is how orderly traffic is in the U.S. At least in most areas...I'm sure there are exceptions. I have the impression they get from American movies that every other driver is a psychopathic killer with an assault rifle on the passenger seat.