Even "in Japan, it is commonly expected to remove shoes and wear slippers provided by the host or brought along by their guests" runs the risk of being side tracked into a thousand or more sidelines.
Even in Hawaii, it is considered rude to wear your "outside shoes" inside. If I recall correctly, and it might have been a different thread, the controversy seemed to be over the unwillingness (or inability) to understand when other cultural practices prevail and "roll with the flow." When I lived on the US Mainland, I thought it an odd, and affected, practice to take off shoes when entering someone's home. My bad 
Although I am now a converted "cats inside only" person, I didn't used to be and I understand both sides of the debate in the US. It wasn't until posting here that I discovered how practices vary around the world. I thought it was cool that we could come here & share, until posters abandoned civil discourse and started bashing each other. 
This illustrates the problem with a list of subjects that get banned because some posters are rude. How can we ever learn enough to understand each other if we can't talk about the topic?
Been to Hawaii and I have an aunt married to a man of Japanese ancestry - they have lived and worked in Japan several times over the course of their marriage. They prefer to run their house "Japanese style" with outdoor shoes kept by the door and people running around barefoot or in slippers (she sews - slippers can be safer - but pins do sweep up on tile or hardwood floors than on carpet).
Some threads have devolved into "but WE think that it is wrong, unsanitary, rude, nasty, or doing it THAT WAY is KINKY" so everyone should do it the way we do it or else........
Shades of Star Trek: Deep Space Nine with a Ferengi making comments about how "kinky" it is for hoo mans to let their women wear clothes, because that just isn't the way the Ferengi do things.............but I digress.
I really don't see wearing shoes or not wearing shoes indoors as a religious issue, a hygienic nightmare due to the possibility of cross-contamination, a political issue, a moral issue (similar to vegans versus omnivores), or something so kinky that it it should only involve consenting adults in private.
But there are apparently people who are so vocal and opinionated about anyone else doing something *different* than their own experience that it rapidly becomes impossible to continue a calm, rational conversation on the subject.
Sometimes it amazes me what subjects those are - I mean, politics & religion were traditionally subjects to be avoided because of the potential for controversy...........but there are a whole host of other subjects that have come up here that have been at least that polarizing.
Which is why the Jane Goodall Observation of Primates techniques on handling things have become a catch phrase here as well.............
