You underestimate the nefarious potential of hidden audio-only recorders. Thieves can loiter in busy locations and record people having an affair to blackmail them, spelling their password on the phone or giving their address to their friend in a bar and ask them to water the plants while they're on vacation next week (indicating that the house will be empty and ripe for burglary next week)...

There's a reason why it's illegal to record people without their consent.

The thing with those audio-recording glasses, as with the Apple spy watch, is that the valid uses cases are few and weak (it's mostly people who are too lazy to take notes in a meeting) but the nefarious use cases are much more numerous.

The important point though is that the devices need to be compelling enough for people to buy them, so the makers can use them as Trojan horses to put their customers and their surroundings under surveillance. And the makers don't care if the usage is legal or ethical, as long as they can get their bugged devices into the hands of their victims.