I imagine a big part of the cost of these professional systems is some sort of liability insurance and certification. What happens when the electrolyte in the caps in the feedback circuitry goes dry and the controller starts getting incorrect inputs? The Thai invention is a volleyball that melts upon contact with flame and releases a pressurized extinguishing agent. It's far better to use something simple and mechanical instead.
I sure no one uses the civil courts more than the insurance industry, so why would anyone do anything other than follow their guideline and requirements?