I understand your confusion Don. Here's the deal. Most electronics, and this included those used on motorcycles are not waterproof. Some are "weather-resistant", but I wouldn't use them in a downpour, or even a light misting for that matter. But we do use them. GPS, sat. radios, mp3/cd players, 2-way radios, radar detectors, etc. The trick is when it starts raining, or you know, or even think it is going to get wet stow them away, or use a water-tight container that will display them.
Now as for "easily detachable" most of these devices, if not all, are attached to the motorcycle in a variety of ways. I use Ram-Mounts, or stow them in my tankbag. Some folks installed them in the rear cowling area, or under their seats, some even install devices in their ST fairing pockets. The possiblities are almost endless. Most can be easily detached and stowed. I hope this helps you understand usage of electronic devices on motorcycles better. And I bet the other guys here can give a better answer.
The Sirius InV sat.-radio is very small, portable and I have mine just laying in my tank bag with the power connected and the antenna hanging out magnet'ed to my gas tank, and a audio cable connected to my helmet speakers . My GPS unit is on a Ram-Mount mounted to my left handlebar. If looks like it is going to rain I remove them and stow them away for a sunny day. I don't like riding in the rain anyway.
Check out this one guy's solution for adding electronic devices to his bike:
https://www.st-owners.com/forums/showthread.php?t=22322