I mean, you know how everyone carries a phone these days? If you use your voice, it could be potentially recorded.
So… we could just use sign language. Teach everyone sign language, use that whenever you wanna say something anti-government.
Its much easier to cover up cameras (or move out of sight) than to cover up microphones. And its unlikely people would want to leave their expensive phone in another room out of sight, so teaching everyone sign language seems like a straight-forward option.
Also, bonus: its very helpful for people with hearing problems if everyone knew sign language.
People usually think that sign language was artificially created to help the deaf people. This is of course very wrong, but tells a lot about how society perceives abledness. In this case we could even talk about being deaf is a disability, but that’s a topic for a other day.
Actually, sign language historically developed similarly to how spoken language developed. This means that even within one country, many different dialects are spoken. This can be easily seen for rather simple words - the word “Friday” for example can be vastly different in one city compared to the other.