I went to several major U.S. websites and didn't find any mention of this story at all. I can find plenty of Trump stories, but zero coverage of what in any sane world would be a major news event.
There's some really good discussion here around what to think of China. I love the Chinese. I'll let others debate what this says about their country and way of life. But this many people being killed in a public and brutal fashion in recent memory by a major world government? The country has nothing to do with it. This is a significant historical fact and it's major new information about a controversial and shocking story from just a few decades ago.
So why no coverage? My guess is that it's about money -- embarrass the Chinese and they'll hurt you in the wallet. But that's just my guess.