Audio surveillance is a different world than recording conversations. This whole "one party consent two party consent" thing is all about a conversation that you are in. Otherwise you're fucking with the wiretap act. If the Trump era has taught us one thing, it's that it comes down to enforcement and who has the best lawyers. But fundamentally? If Amazon distributes a system to landlords that allows them to violate the law, knowingly or not, Amazon would likely get the opportunity to prove that they aren't liable for doing so. It would also be really, really shitty for their brand. This is the fun of hidden camera shows, and why every security camera you've ever seen doesn't have a microphone on it. US law has a much dimmer view of audio surveillance than they do of video surveillance (not that video surveillance via an Alexa would be hunky dory, either - reasonable expectation of privacy is pretty easily established).