I think its sad that we have to frame it this way. This is just manners versus lack of manners.
Its not a different culture. Its a lack of culture.
There is no excuse for constantly interrupting people. Its disrespectful and counterproductive.
There is a bit of subtlety also in that interrupting in the middle of a word is more rude than in the middle of a sentence versus a paragraph.
If, for example, someone has completed the third sentence of a paragraph that is clearly wrapping up, and pauses longer before what apparently may be the fourth sentence, but the other person thinks they have already got the message, it might not necessarily be rude at all to start talking before the last (probably not really important) sentence comes out. Sometimes it depends on the context and how long the pause is.
Lack of common courtesy is unfortunately very common. That doesn't mean we should accept it without comment.
Most contexts globally where there is education and respect will show this type of common courtesy. If there is a lack of respect of education or both, more rude interruption is likely. I think there are for example some contexts or cultures where there is less respect, for example some executives talking to workers in certain countries. But it's not excusable and the workers there who are the majority in that country will not have the same behavior.
Not trolling. The reality is that many people are ignorant, impolite and/or disrespectful. I try to avoid them. That's one reason I don't have a lot of social interactions. I am just not very tolerant of trash.
Its not a different culture. Its a lack of culture.
There is no excuse for constantly interrupting people. Its disrespectful and counterproductive.
There is a bit of subtlety also in that interrupting in the middle of a word is more rude than in the middle of a sentence versus a paragraph.
If, for example, someone has completed the third sentence of a paragraph that is clearly wrapping up, and pauses longer before what apparently may be the fourth sentence, but the other person thinks they have already got the message, it might not necessarily be rude at all to start talking before the last (probably not really important) sentence comes out. Sometimes it depends on the context and how long the pause is.
Lack of common courtesy is unfortunately very common. That doesn't mean we should accept it without comment.