I am reminded of the scene of a guy walking through various layers of security to access a computer that isn't connected to any network and still wonder what the hell this guy's job was in Mission Impossible (1996). The data got stolen either way, because of course it did, but what highly sensitive work can you even do on a computer not connected to any network?
If there's too much security in the way, it seems to me that work becomes impossible.
We had water and traffic control and electricity for decades and centuries before the Internet. It is less convenient and more expensive, but it also means hostile countries can't literally poison your drinking water from across the planet. It's not a difficult trade to consider.
Is it really more expensive to not connect a water treatment plant to the internet? I can imagine the vendor selling that idea but I struggle to come up with how that could make a water treatment plant cheaper to operate.
Yes. Without a remote system you must have a real person check levels, pumps, pressures, and many other devices thus be present. This person must be trained and you will likely need a backup as well.
If not a person you need more redundancies built in. Bigger tanks, multiple backup systems. When items start failing you need them to be shutoff in a timely manner. Water pumps at these facilities are in the 50-100k range. When it starts failing you want to know.
Think of it like driving a car and it starts making funny noises. The longer you wait to fix it the more it costs.
The expense usually comes in operations. By connecting the water treatment plant to the Internet and making it remotely operable, you can have one guy who sits in an office and is responsible for overseeing the water quality at many different treatment plants. If everything is local, you need one guy on site at each different plant. People are expensive, software is cheap.
Of course, by making it remotely operable, that one guy could be replaced with a guy in Russia who's job is to poison everyone.
>what highly sensitive work can you even do on a computer not connected to any network?
https://en.wikipedia.org/wiki/Sneakernet
William Donloe is played by Rolf Saxon, he's an analyst working for the CIA in the movie. A different installment of the series reveals additional information!