I think this happens more than we care to think. I had an ex-scio tell me that they had been held against their will at Flag for seven days and told that they couldn't fly home. They missed family coming home for Christmas and the birth of a grandchild because CoS thought it was in their best interest to stay at flag for the holiday. This happened abut eight years ago, but I wouldn't be surprised if it still does.
I don't know the details of how they were stopped from leaving, I was too annoyed by that point in the conversation to care to ask.
Well, there is a difference between being "detained" or handled to stay for more service and being thrown in a room and locked in. The former happens all the time. The latter, outside the SO at least, is a less common occurrence. But yes, it happens. And you're right, it doesn't always make the news. I can think of a few Type 3 watches that I knew of that I've never seen anything about online.
An organized Church is a control system by its hierarchal nature. William S. Burroughs, Naked Scientology