The notion of appropriateness, I think, has different kind of weights in Japan and in the US.
In terms of social manner, although codes are different, both cultures share similar sensitivity. It is also same that the older and more conservative segments of people are more keen on taking them seriously.
In political situation, however, US is way more sensitive about appropriateness or correctness (sometimes excessively so, IMO) on race, sex, etc. This is not surprising from historical and cultural background of each country.
But in terms behavioral appropriateness, I don't hear much about it in the US, while in Japan it is a pretty big deal(again sometimes excessively so, IMO). I saw an casual poll on "un-adultlike behaviour" at a Japanese site.(you can see a fantastic translation here.)
This includes things like having no savings, inability to cook or clean, improper use of chopsticks, and calling parents as Mama and Papa. They are cute and harmless for the most part. Heavy things are not in here, probably because most people are trying so hard to do them right under tremendous social pressure.
Japanese expect you to act in certain ways depending on types of job and it is actually one of the reasons why their services are so good, even though there is no tipping involved. But playing the perfect mother, daughter-in-law, subordinate, the nice guy, etc - this never ending list can be daunting challenge for many people.
Now, let me tell you what I thought un-adultlike when I came to the US. Grownups are drinking soda all the time! Men eat lots of sweets in public! These are somewhat wired to me to this day, but that's ok, we love our manga too.