China has a 240-hour visa-free transit policy for foreigners. Most major cities have direct flights—come and see China! (Remember to download Alipay in advance and link your Visa card.)
I can accept a facial scan, but I draw the line at fingerprints and more invasive biometrics.
At an airport, there was a sign that said "Stand in front of the camera and we'll tell you the way to your gate.". It scanned my face, and on the screen it showed me my name (I guess to make sure it's the correct person), my gate, and how to walk there. I never consented to this commercial use...
Although it's probably mostly a legal impediment, I can imagine if the authorities spotted an event and need to track a suspect, they can put all the footage into a system and it will return a sequence of videos/angles in which the suspect was seen.
They already have everything on us, and I mean everything.