They only show enough to scare people. Nobody is stupid enough to blab military secrets.
In the USA nobody knows how many First Nations there are because a lot of them refuse to reveal their numbers to the US government. These folks have already lost a war and they STILL refuse to expose their position to the enemy!
In the military race between defensive capabilities and offensive weapons ... the offense will always win. That's why we don't rely on set defensive systems anymore.
So what if everybody knows our Navy has high-powered laser systems, and electro-magnetic rail guns?
Sure, you can take out a lot of our systems with an EMP blast. But then you're in the same low-tech situation we are. And grunts-with-rifles haven't really changed that much since WW2.