Yeah, but it's sadly common. I have personal experience with two such situations in my work over the last 16 years and I'm just some two-bit general IT contract

Yeah, but it's sadly common. I have personal experience with two such situations in my work over the last 16 years and I'm just some two-bit general IT contractor in Ohio, US. Until the decision makers who demand the interconnection of these networks are held accountable it's isn't going to stop. The cases I've seen have been to facilitate 24x7 off-site PLC vendor support access. I certainly see the business argument for the economics of off-site support for infrequently/improbably failure scenarios. At the very least, though, some type of physical interlock could have been employed (at the expense of some response time). Edit: I think controls can exist to make this kind of situation tenable for at least some types of industrial controls applications. When you start getting to things like municipal water and power I start getting more antsy.