Dear Reader. Before you consign this blog to the pile of TL;DR articles I'll cut to the chase. Americans are no more and no less stupid than any other race. I know many intelligent Americans and am proud to call them friends. That then is what they are not, so what are they?
A brief segue. My late father, and my brother enjoy/ed hiking in the great outdoors. Picture the scene. A sunny day in a car park, a 1000 foot mountain in front of you. You and your partner are attired in warm clothes, shod in leather hiking boots, both carrying haversacks stocked with all the equipment you would need should an unforeseen event occur, including assisting a third party who has had an accident and isn't so well prepared. You are surrounded by a throng of people wearing jeans, tshirt, and trainers [US: sneakers]. They are ill-prepared.
In the analogy above the latter larger group are Americans encountering a culture different from theirs. They are not stupid, they are ill-prepared for the encounter.
Whose fault is this? Is it anyone's? No not really. The root cause goes back, I think, to the Mayflower in 1620, and the nature of the settlers. They were English Puritans, and brought with them, two things I think. Their religion, obviously, and their culture. The nascent British Empire had already begun laying down its roots in the late 16th century. Characterised by, if any single thing, transplanting English culture into whatever country they absorbed into the Empire, believing their way was better than that of the indigenous peoples'. The most visible sign of that, to this day, is the number of Commonwealth countries, and ex-colonies which show English architecture, particularly in their municipal buildings. I don't think it's a stretch to believe the settlers also thought their way was better than the native population's.
172 years later comes US Independence, but that was a political separation, not societal or mindset separation. Thus you have a population who at their core believe their way is best. Haven't they just bested a very well trained and equipped army? There then is their proof they are better.
234 years and several generations later that belief has largely not been tested. Very many Americans have never left the USA. Thus when they do, they carry that belief with them, and the misconception that 'because America is best every other country does things their way'. Then rather rudely reality intrudes and points out the ways in which many things are done differently in other countries. Unfortunately here the US Education system takes a large chunk of the blame for instilling in students a belief that their way is always the right way.
This is particularly the case in Britain where an American will assume that just because the British speak English that they speak - and spell in - the same dialect of English they do, and if there is a difference - say in spelling - then the British citizen is wrong. They're not being arrogant when they try to correct you, they think they are helping you correct an error and are confused when their help isn't gratefully received. There's a reason that when you set up a computer several of the language options are variations of English, and why spell-checkers have, for example, a British-English dictionary.. and no it's not to ensure you spell words wrongly *lol*
The armed forces has an acronym called the 6Ps. Proper Preparation Prevents P*ss Poor Performance.
Americans in general are not Properly Prepared for an encounter with another culture. The result is inevitable. P*ss Poor Performance.