Without realising and without having had to set it up themselves.

So? The vast majority of IPv4 users also do not realize and did not have to set it up themselves.

No, but the vast majority of people who understand enough IPv4 to set up a home or small office network still don't understand IPv6.

There's basically nothing toconfigure with IPv6.

With IPv4 you need an addres, a gateway, netmasks, DNS.

On v6, as long as you have a working router sending RADV packets, clients will self-configure via SLAAC. Granted, same with IPv4 and DHCP.

If you don't have a router, most things should work thanks to link-local+mDNS.

You can easily pop a second router on the network to bridge two LANs, no need to reconfigure the DHCP. Gateways self-advertise, etc.

The point I'm trying to make is that most people trying toconfigure their IPv4 network have a functional IPv6 network the moment they put the cables in (on Linuxes es at least, not sure about other platforms).

Is that mostly mobile phones while on cellular data, perhaps?

I am sure a large percent of it is. That being said in my area I only have 2 choices in ISP and both support 'dynamic' ipv6 and have for 3-4 years.