Disabling bodycams/walkie talkies when visiting family member for privacy, worth the battle?

You should check what the laws are in your state about being videoed and voice recorded, since they can vary. Also what rooms in the house are under surveillance. Then there's the issue of you messing with someone else's system in their own house. If you want to have a private conversation with your Mom, can't you take her outside to do it?

If your sister thinks it’s useful to monitor your parent for safety, I’d suggest you go along with it. If you really want to talk privately, perhaps disconnect the audio but leave the visual monitoring – or take M for an outing and talk then. That’s if things are ‘normal’ and on the level. Most conversations are probably too boring to bother monitoring anyway!

If the relationship with your sister is not good – for example your sister thinks you are telling M that she is being abused, ripped off, underfed etc, or if your visits upset M – that’s a different matter. However if S is doing most of the caring, it’s best to cut her some slack.