[0] "To change the volume, say 'Hey, Siri,' then say something like 'Turn down the volume.'" -- https://support.apple.com/en-us/HT212203
Not that I disagree with your main point; I refuse to use Siri in public, like you say, it’s humiliating.
I’m afraid the joyless Siri just ignores you when you say that.
The best part is that whereas with most commands, if Alexa has any doubt about what you said or you weren’t clear it always asks you to clarify or disambiguate, even various stop/pause/volume-down/mute commands - but when spoken with an angry tone or with an f-bomb or two then she defaults to stopping without question, even if she didn’t hear you clearly.
Like if you say "Alexa, please mute", you could unlock a new voice or a funny joke or something.
Parallel evidence: the Ring acquisition has aggressively integrated itself with police forces.
Partial evidence: some of the devices are known to retain data even after being reset to factory settings (I presume it's a bug).
It has to be listening all the time for its activation command and we have no idea what it's doing with the data that comes in and is determined not to be the activation command.
I do wish there was a way to do it by touching the headphones though. I held off on buying AirPods for a few years mostly for that reason.
Apple's ear buds are the only ones that fit comfortably in my ears so it's sorta my only choice. (The pros do not, which is unfortunate.)
I don't typically run with headphones in so that's not an issue, but even if I did, it's pretty easy to hit the volume button on my phone unless it's in a backpack or something.
iPhone has squeeze your pocket to change the volume adjustments.
Apple Watch has volume control just using a crown.
AirPods Pro too small to handle a moment or twist.
AirPods Max trials on-head crown and whole better than other product physical controls, quality fine physical gradient control on even a large mounted device is tricky.
I'm always a bit embarrassed when I'm in public and a buddy calls me over to look at something on a MacBook. Like - "No it wasn't me who fell for Apple marketing."