RF as in radio. Radio waves have this nasty habit of leaking out past the fence: https://cyote.inl.gov/content/uploads/24/2025/12/CyOTE-Case-...

In water/wastewater much of infrastructure is physically remote and physical security is the typical engineering trade offs. https://validmfg.com/product/lift-station/

Inside this box you have access to the “production” network, if you will. Unfortunately, most SCADA systems implicitly trust their RTUs/PLCs, so this has always been a weak point for the system. Hopefully the situation has improved.

The reality is that critical infrastructure is rarely tested against genuine hostility, except in times of war. There is “cyber” activity going on all the time, but attacks that require physical proximity will probably only happen when things have escalated to hardware. Hopefully the NSA’s of the world run “pen testing” for these companies from time to time.