Hmmm, suppose it's something they'll get around to in the Future, goodness knows what subnets are operating out there.
Wikileaks (plus numerous high level intrusions) showed why Governments should not be on the WWW, or The Internet. Then again; transparency of Governments is a good thing really.
Seperating Government from Internet, and WWW, would depress a lot of public servants though. No gaming, or Porn makes for a grumpy public Servant ...
Mike:
To have more than one internet, by definition, will mean to have a bunch of computers/routers on one segment completely inaccessible from computers/routers on another segment.
Sounds real simple Mike, let's do it

Not at all impossible.
Modulation, DeModulation, and Parity checks; is how a Modem, or 'Router' decides what data it has been instructed to receive, and send. Let's Encrypt and be seperate in certain instances.
Let's not get confused by a LAN (Local Area Network.)
Your Local Supermarket uses a LAN, (no access to WWW). My Chemist does too, I asked them. University - ones I've been to - have a LAN between Campuses, I remember waiting 20 minutes for my workstation to boot

; plus we had limited Internet connectivity options too. That's going back a few years now.
I say the best answer, although each is fantastic, thanks for all replies !! - that fits in with my head in the clouds pondering ...
kjpetrie:
There are all these things. They're called VPNs and they run on the same infrastructure, but encrypted. However, while businesses want to sell to consumers they need to be in a common space where they can be found.
Virtual private networkUser-created remote access VPNs may use passwords, biometrics, two-factor authentication or other cryptographic methods.
Network-to-network tunnels often use passwords or digital certificates, as they permanently store the key to allow the tunnel to establish automatically and without intervention from the user.
MORE ...Thanks for people who thought about it, and those who said it can't happen

Basically slicing the WWW would be a real pain in the Uhum
