[quake]

Your arguments are almost identical to the ones greybeard embedded devs have against the Arduino. Yeah, it's expensive, uses an outdated micro (at least the AVR-based Arduinos), but it's effective because of its popularity. Basically a flywheel effect. Doesn't have to be good or optimal, just has to be flexible and have a big community.

I doubt anyone is using an off the shelf Pi with SD card for an actual safety critical deployment and expect to get it certified. There are options like the Revolution Pi which is half PLC and uses the Pi's Broadcom SOC for non-safety calculations. Some even support CODESYS.

I agree that most ARM embedded Linux SOC's can be absolute dumpster fires when it comes to peripheral documentation and poorly maintained device trees (looking at you, Texas Instruments!!!) but that's nothing new in embedded dev. Learning how each manufacturer/platform do hardware peripherals is half the battle.

So I agree that the pi isn't always the best device for an application. Cost and power savings on an ESP32, better processing on your old laptop-turned-server, and so on. But the Pi does have excellent documentation, and was lucky enough to gain enough traction to create an ecosystem that reduces friction to just get something running for beginners, which is literally its original design intention.

[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.