It would be hard to argue the wiretap laws apply to recording ultrasonic sounds extracting data from them. Honestly their isn't even the need for the device to store the audio, much less send it off the device.
Microphone access, especially if it's always-on to listen for the cue, is going to end up recording conversations, and those conversations will almost certainly involve people who are not the phone's owner and so could not have consented to having that phone record them.
(also there's the general problem of devices "helpfully" listening all the time for magic phrases like "Hey Siri" or "OK Google")
Having microphone access dosent equal illegal wiretapping, sure it might be a prerequisite. Yet you need to prove more than that the app could illegaly wiretap you if the developer wanted to do that to use the law to go after these apps
