I think UL just approves it for safety, not "works as advertised". It would be hard to sell an electrical gadget without UL approval. and your $199 had to go for something
For a product like that the UL Listing is just about safety. It doesnt have to work...it just has to be safe.
For a UL Listing of alarm equipment, medical equipment etc it has to work or it doesnt get Listed.
I had looked at those a few years ago. I agree with Jknox that the concept is irrelevant for residential applications. With commercial use the "concept" may be valid since they are billed on peak usage and time of day etc. in most cases.
That device is basically......... a piece of ^&* in my opinion.