can be difficult to get a US visa if they are falun gong.
whatever the reason they don´t feel safe in China that´s why they flee political perseculation. US is a natural choice because it is far away it has no expulsion treaty with China.
very difficult to hide for everyone. Ccp has a comprehensive survilance system in place that can monitor every citizen where they go where they live. Police is your friend. 1 police officer for 3 inhabitants (1 policier pour 3 habitants). they can visit you without invite (en Chine, la police rentre chez vous sans raison!).