I think China erred by sending such a large balloon that was visible to the naked eye, causing the American public to demand it be shot down. There's no hard rule about where national airspace ends and space begins.. a lot of times they fly too high for planes to reach, and under certain circumstances balloons are allowed through national airspace.. so if the balloon isn't causing a problem (like being a hazard to ai…
You mean saw with their eyes or on the news? If it was with their eyes then it wouldn't lead to public demand since as you say "weather balloons fly through our airspace all the time." and there's no way to attribute it to another country. If it's on the news then physical size is not relevant but detectability and newsworthiness are. People would have cared.