China spares no expense when it comes to surveillance. No “communist” countries do. They can afford to have a person watch every foreigner personally. I doubt these are high paying jobs. It’s for the glory of the state, comrade.
Monitoring FaceTime calls would be expensive to set up but not all that expensive to maintain. And again, expense is not an issue. They don’t call it the Great Firewall for nothing.
According to Microsoft, the Chinese stole very secret encryption keys and used them to break into US government and Microsoft servers. I think China could get the keys for FaceTime or whatever else they want.
They mandated a few years ago that all servers serving Chinese users must be in China. All of Apple’s encryption works so seamlessly because Apple manages a lot of keys. Well, Apple’s servers do. The ones in China, for the Chinese users. They don’t actually have to steal anything in this case.