Home Automation (HA) is sub-branch of Building Automation, which is a discipline originated in turn from Industrial Automation which target is to control automatic machines or plants. This last one’s symbol par excellence is surely the PLC (Programmable Logic Controller). It is thus natural the presence of several common aspects between Home-Building Automation and Industrial Automation, because they afford the same problem of controlling devices by command modules, both of then located in a wide area, often using remote sensors, with the need of connecting actuators, command modules and sensors by means of a net infrastructure.
One of the main differences is that most of the time a HAs has a distributed architecture, while a machine automation system has a centralized one. This means that the program that runs on the PLC controls almost everything, while the input/output modules only execute the simple actions they are commanded for.
The criticism is obviously true, PLCs are very robust and affordable devices, and the probability of a failure is very rare. Also the error probability of fieldbuses in the communication tasks is very low, so, even in the case of centralized structure, the system could be considered affordable and stable. It is very common to use directly PLCs to implement Home Automation system.