This is about expectations. not technical features. If you walk into any random home, can you expect that your conversation is private? Today, that's already hard to answer because you first have to know if there are any Google, Amazon, Apple, or other devices that might start transmitting your conversation to a 3rd party. Do you know every possible wake word used by every devices with this kind of feature?

At some point it is impossible to know the list of possible words you cannot speak and the public will simply start assuming that they may be recorded anyway. When that perception changes, so will legal doctrines.