It's actually not all that difficult to spot vpn traffic. Run some DPI and just simply look at the size of the packets being exchanged.
You are talking simple in THEORY, but not in practice. We're talking about sniffing the traffic of a COUNTRY, not a small office. That takes serious hardware and serious money if they don't want to crawl. Sounds like they are ready to turn on some system. But like all things internet, it will only take a short time for people to learn how to get around it.