

Wireguard is not difficult to block either, it’s not designed to be hidden. China, Russia, etc have learned long ago how to detect and block it. The only semi-reliable way to bypass sophisticated VPN blocking techniques is to use protocols that mask as regular https traffic (and self-host it since well know public VPNs will of course be dealt with by simply blocking packets to their ip addresses).
Yeah OpenVPN is often used for business reasons (e.g. by remote workers), so it’s usually not blocked wholesale, only throttled (and known public VPNs providers and blocked via blacklisting their endpoints’ ip addresses). Wireguard meanwhile is used much more rarely so there is less fallout from blocking it completely.