Wait are you saying you can be standing right next to the RCC and couldn't see the icon because it's in the host? what's the point of onsite hacking then?
When you hack a device, it defends with Device Rating + Firewall (in most cases anyway, sometimes Data Processing).
So let's say you want to hack a camera, with a DR3: it's defence roll is 3+3 = 6d.
When a device is slaved to a Host (or anything for that matter), you use the best from the device or the Master.
So if your camera is slaved to a Host with a rating of 6 and 9 in firewall, the defence roll is max(Camera DR, Host DR) + max(Camera FW, Host FW) = 6 + 9 = 15
If you connect directly to the camera, then it only has its own attributes to defend, which means it's back to 6d instead of 15.
Plus, any mark you get on the camera, you also get on the Host.
And that is why you may want to be on site to hack stuff, especially high level hosts.
It works the same way if you want to spot the RCC: it's defended by the Host, so the Matrix Perception roll may be much more difficult (depending on the RCC and the Host of course).
Once in the Host however, you're able to see every slaved device, no rolls needed.