And if you're not going the automation route, make personal service a differentiator. In the UK we have the Everyman Cinemas doing this for example, offering sofas with tables, a table service for food and drink, knowledgeable and enthusiastic staff, etc.
Well, I suppose the first question is whether or not your automated monitor contains a Mysterious Hum Detector, and whether or not the case of a Mysterious Hum happens frequently enough to be worth rolling out the Mysterious Hum Detector to every screen in every one of your cinemas.
Also: The Audio Has Accidentally Been Set To French detector, and the Dammit Something Has Fallen In Front Of The Projector detector are equally hard to implement.
Automating uncommon real-world events is significantly harder than you might think.
But I agree with you that it would be relatively pointless - any resolution to a problem like that probably needs physical intervention to resolve.
And anyways that theater was full of mysterious Hum detectors. The article was written by one!
Probably take about 9 months to build an MVP, but about 16 years worth of training data until it's able to handle most cases.