The problem here is greed! If all the infrastructure required only human hands at the valves. Yo could put semi-retired operators in cottages connected to old landlines. And operating the system manually.

Very possible if CEO's salaries and director entitlements were comparative with 1930s comparisons!

Cyberware attacks and ransomware, only possible if there's too much reliance on automated systems! Particularly in energy distribution.

Moreover, if the economic paradigm leaned far further toward cooperative capitalism instead of dog eat dog extreme exploitative capitalism with its totally unproductive drone investor body in the mix, even less possible.

While I applaud Automation in manufacturing where the system can be totally enclosed from outside interference inside a single highly integrated facility/site.

If we're to use high-tech solutions? then they need to be connected to quantum computing and opened only with passwords that only the operators can use or know.

I'd tell you how that could be done, but then I'd have to shoot you.
Alan B.

The best solution is do not connect critical infrastructure to the internet !