Not the OP, but they can be disabled in the phone, and many people, like me, have those disabled.

If you don't trust Apple/Google enough to have one of their standalone assistants in your home, how can you trust them enough to believe disabling the workalike assistant on your phone actually truly disables it?

Because I expect, even if naively, for things to work as described.

If a phone assistant is disabled, I believe it is indeed disabled.

If there is a listening device in the home, I expect it to be listening all the time.

I don't understand what the confusion is.

The "listening device in the home" is described to only listen to the wake word.

Umm.. how does it know that the wake word was said if it's not listening all the time?

It has a special circuit that can literally only recognize the wake word. You have to trust that the circuit does that. Same as the "disable Siri" button on your phone.

Phone battery life creates a constraint on the phone's ability to perform constant surveillance. An assistant that plugs into the wall lacks this constraint.

To me, this is a big difference.

Apple isn’t making the smart thermostats, google is. I had a lecture at school where nests business model was in part to monetize home owners electrical and heating use data (eg, to optimize electrical grids).

It's massively more likely to hit some bug and record a bunch of me when the listening feature is enabled than when it's not.