If you want an intercom system that's usually silent until it's needed to be used, then push-to-talk controls are one answer. The mike is muted until you press/flick a switch to open the mike.
I don't use these on general stations, I'd only use them on special ones, for the following reasons:
If the operator is using both hands to do their job, they can't press a PTT switch at the same time. They have to stop what they're doing, and reach for a switch. This causes a delay, an interruption to live work, and people may stop communicating because of the inconvience.
While a PTT switch could be mounted on the equipment, right next to where their hands already are, pushing a button on a tripod arm can wobble the tripod head and ruin a shot.
People forget to push the switch, and talk into a muted mike.
People leave the switch on, and invalidate the point of having a talk/mute switch (switches that can lock on are essential for some tasks where the person needs to use both hands for other things).