Can't help but think of the Star Trek TOS episode where Kirk is accused of murder and they find the "murder victim" in the ship by identifying and isolating heart beats until they discover he must still be aboard. It's been almost 60 years since the episode came out, but still sorry if that's a spoiler
Classic Star Trek (speaking as a fan). They can scan an entire planet to find a lost crew member, but can’t tell how many people are on their own ship. And they have universal audio surveillance on the ship but still have to use wall intercoms.
My phone can hear me and answer whenever I talk to it, but I still prefer to push a button first (kinda intercom), or even just type :)