They've got different channels/frequencies you can choose from. Most 2-ways have around 14 frequencies to choose from, so everyone on your team sets their radio to your channel. Your opponents will choose a different channel, and you won't know what channel they're using.
Now, it is possible for your opponents to be monitoring the other channel, but IMO, if you can trust someone to call their hits, you can trust them to stay on their channel. And it's usually too much of a hassle to monitor every single station in order to figure out what channel your opponent's using, when you may or may not get any useful information out of it.
EDIT:
Of course, so guys who get radios that cost upwards of $200, and those can sometimes be encrypted. But then again, a $200 radio wont give you that much of an advantage over a $40 one.
EDIT #2:
Throat mics are like headsets where the microphone goes directly on your vocal chords so that it will pick up your voice even when you are being very quiet. They're useful if you like to be sneaky.
Last edited by Admin on 30.11.10 12:35; edited 2 times in total