Sure, if the system is set up to only respond to very specific commands that humans would not respond to, I guess that could work. I was thinking more about the other way around, where a person might speak to someone else in the room and be overheard and acted upon - "turn on the lights!" could be a command for the computer controlling the room, or the human standing next to the Christmas tree, for example.
I’ve never had Alexa control a device via a TV show’ audio but playing back a video of me testing my home automation (“Alex, do X”) triggered my lights.
I’d love a no-wake-word world where something locally was always chewing on what you said but I’m not sure how well it would work in practice.
I think it would only take 1-2 instances of it hearing “Hey, who turned off the lights?” in a show turning off my lights for real (and scaring the crap out of me). Doctor Who isn’t particularly scary but if I was watching Silence in the Library and that line turned off my lights I’d be spoked and it would take me a hot minute to realize what happened.
But also, post-fix wake word would also be natural if it was recording all the time. "turn on the lights, Google", for instance