There is no such thing as "the law" in China. You may be imprisoned or disappeared if you didn't do anything to circumvent "the law", there are always undisclosed "relevant rules and regulations" ready to be unleashed. You can also carry out brazen illegal activities as long as you are well-connected (until you start stepping on toes of someone more well-connected than you).
So what if email is insecure, neither is Wechat. And encrypted email is still a thing.
Just because there isn't "the party" making decisions in the US doesn't mean that there isn't a lot of flexibility in when and how the law is applied. It just gets left up to the local sheriff or prosecutors.
So what if email is insecure, neither is Wechat. And encrypted email is still a thing.