But the most unrealistic part of this story is how all the IoT automation continues to work in the absence of the Internet.
"Bluetooth device connected"
"Bluetooth device connected"
It's actually one way this story about the apocalypse is more hopeful than the present day. We don't need the internet to make most of the things in that story work, but in our timeline we'd add it anyway to get and sell those good analytics.
And no one has really come up with an alternative: home assistant is good, but it's not for the non-techy.
I will squarely blame IPv4 for some of this: NAT has meant that the key application people might want to use is broken by default (remote device access) without mediation servers.
No, practicality is not the main reason these unnecessary connections are added. The main reasons are 1. to sell and enforce subscriptions and 2. to collect and sell data.
Is it just easier to get your car seat warmers to work when they can connect to the internet and make sure you're paid up?
It is much, much easier to do things when central server is around. This is especially true for embedded devices which have limited resources and cannot be updated easily and safely. Close all the incoming ports and the chances of your device joining the botnet fall dramatically. Keep that port open and you'll see yourself mentioned all over the net in the context of "horrible security, don't buy".
The only hope is multi-vendor systems which connect to central hub - zigbee, matter, etc.. - but sadly they not very popular, as wifi is everywhere, access is cheap (the chip can found for under $1 today), and hub-based are harder to get started with.
Being tied to the internet happens because manufacturers want to be able to watch your usage, sell you ads, and make you buy more stuff from them when they decided your existing hardware is "too old" and shouldn't be supported anymore.
Not a luddite but, aside from a couple of Alexas, just no need for any IoT.