In China, we have a some sort of social phenomenon called "Herd behavior"[0], simply put: If something is popular in crowd, then it tend to be more popular.
Also, I found that most Chinese people are lack of motion of trying something new: If something works, then we'll keep using it and stop worrying about it until it breaks.
> I've forced the people I talk to the most to get signal.
In China, this hardly works, because people you try to convincing may also binded to WeChat by their contacts. So a easier choice for them is just to silently ditch you.
(Of course, dad and mom are more likely to stick with whatever chat service you're using, so :DDDD)
BTW: There are no encrypted chat service in China, and Chinese people don't care too much of their privacy (By western standard).
So if you tell them: We should not let government listening our conversations, let's use Signal! You will usually get replies like: Yes, just let them listen, I have nothing to hide. And keep using WeChat.
[0] https://en.wikipedia.org/wiki/Herd_behavior#Everyday_decisio...
Is it cultural? I use signal. Most of my contacts don't use signal. I've forced the people I talk to the most to get signal. For everyone else, I'll use WhatsApp or just text. I don't need everyone to use something for me to use that thing. In fact, the day my mum joins Snapchat will be the day I'll uninstall it for good.