[petsfed]

I once encountered a hydroponic nutrient dosing system that was, no shit, a RPi 3+ with a custom HAT for the electrochemistry and actuation. These were sold to businesses running container farms and the like.

At the end of the day, it seemed like the manufacturer had the (good) idea to automate the dosing, but thought that all the standard industrial automation tactics (PLCs, ladder logic, HMIs, etc) were somehow overkill for the application.

Which meant that the end users had to write all the software to make it work with a standard industrial automation system anyway. It was super annoying.