"An off switch?! She'll get twenty years for that!"
"Why is taxi advertising so effective", it asked me. Why indeed.
The ones in China have a mute button, but alas no off button.
Heinlein predicted it first
Looks like a good use for full sheet self-adhesive decals.
The ones here in Vegas have a language selection button. If you hit it, the device stays quiet on the language selection screen for the rest of your ride.
You can mute them in New York. Well, most of the time.
Until the driver thinks it crashed and reboots it from the front seat.