This is clearly lighthearted but some posters are getting very defensive!
Please accept this is the spirit it is intended.
As a Brit who has lived in many different countries, I can find things that baffle me in all of them. A short list:
No mixer taps in the U.K. Old houses, I understand, but even in some in some of the newer places.
Washing up bowls. Yeah, still don’t get it despite growing up with a granny that used them.
Re: basements - yes, the extra storage space is amazing however they can only be built in areas with very low water tables. The U.K. water table is very high in comparison with, say, Boston. Small local variation do apply.
Australian obsession with coffee. It has become snobbery for a country that like to pride itself on egalitarianism.
Whilst we are on the subject of Australia, the language. Why did you have to take a perfectly serviceable language and a) abbreviate everything with more than one syllable and b) start using weird phrases like ‘front court’ and ‘stoush’ (and those are just the ones I can think of now). I have actually had to check that I understand their meaning by asking people or checking a dictionary. And I’m an English teacher!
And Aussies love to travel...but not in their own country. I saw more of Australia in my first 5 years of living there than people who had been born in the country and lived there for 40-50 years! I still haven’t been to Bali though and it is entirely possible I am the only person in the whole country that hasn’t.
American obsession with gun ownership. Yes, it is part of the culture but it still baffles me as to why an assault rifle can be sold for deer hunting.
For any Americans wanting a kettle - Walmart was selling them two years ago. I can’t comment on the energy consumption but oh my gosh, they are so much more convenient than stove top kettles and I just don’t understand microwaving a cup of water to make coffee. Use a bloody (electric) kettle!
Why don’t Americans like to have books on show? I know American who are well educated and well read but they shove books in closets instead of putting them on shelves. (Is it because they have so many closets and need to find a purpose for them all?)
I agree that American kitchens all look 6-12 years out of date compared to the U.K. The property brothers are very cute but all of their kitchens look the same.
Eastern European (and German) toilets with poop shelves - I understand why they exist but, yeah, still find it weird.
French women and scarves - looks lovely and part of the classic, signature look but is it really practical when it is 35* and sunny? Fashion should follow function, not the other way around.
Malaysia & the Philippines - women have children very young, move overseas for work and let the grandparents raise them before returning to raise their own grandchildren. I’ve seen this repeated across generations. Why not work first then have kids so you can raise them yourself? I do wonder if I am missing part of the economic argument here.