I've been to both Changi and SFO - in SFO i walked more or less straight from the plane and out. Same experience when I departed. In Changi i was detained becau

I've been to both Changi and SFO - in SFO i walked more or less straight from the plane and out. Same experience when I departed. In Changi i was detained because of reasons they would not tell me. I was placed in a room with a lot of seats and was not allowed to make phone calls or ask any questions. At one point I stood up to walk to the desk and ask why I was detained and they immediately said I had to sit down and be quiet.