CruzinDux, and others.
To better understand why the radio does what it does you first have to understand that it was built for use in a car or truck, it is not a specially made unit for an RV, and certainly not for an Airstream.
As designed by the maker, for a car the radio has two 12 volt
input wires. One supplies the power to run the radio when the car is in operation, that is when the car key is on either in the running mode or accessory mode. It supplies the power to run the radio circuits and amplifier as well as the display. It switches on and off with the key. Thus the display shuts off every time the key is off. Works great in the car.
The other input wire is connected directly to the car 12 volt
system in a location which is always hot. That is full time 12 volt
power, never turned off unless the car battery is disconnected, as when it is changed for a new one. This wire controls the radio station pre sets, runs the clock (but not the clock display), and in general keeps the memory hot all the time. It takes relatively little power to do this, maybe 10 to 15 mA in many cases. Since the car is used frequently, the large car battery is not run down and stressed by this situation. It is recharged by the alternator, and the car can sit probably a month or so with no real issues. No lights are on in the display.
Now, when that same auto radio is put into an RV such as an Airstream, what does the manufacturer do with the two input wires? There is no Ignition key switch to allow things like the display lights to be turned off when not needed. So what normally happens is the two wires are hooked together and the display lights and clock (if the radio has a clock) are always on. Turn the radio off, the clock time displays. Unfortunately this can take a LOT more power 24/7/365. The display may take 100 mA to almost 1 full amp in the case of the disco/demo display on the Pioneer radio in question. In a car, the ignition switch turns the display off, not so in the RV, as there is no ignition switch. To further drive you nuts, the default mode, if the total power is removed, comes back on. In this case the default mode is the disco light display. So, if you remove all power from the radio, back to square one, like it was new out of the box.
In the Airstream all power is removed from the radio if the USE/STORE switch is placed in STORE and the trailer is not plugged into grid power. Now lets say you are storing the Airstream in a location where no grid power is available. You have the switch in STORE, all is shut down, you believe. And mostly it is. The radio is shut down and no power is being used by it at all.
But you stop in to check it out one day, and on entry, you hit the USE button so you can have some lights for a short time. That turns the radio on (in the default mode, the disco lights). It is behind a cabinet door and you don't see the lights on. You go out and forget to push the STORE mode. Or you deliberately say, hell, I am going to be back next week, and I didn't leave any lights on, so no big deal. But it is a big deal, the radio went active and is taking a full amp (the measurement on mine) to run the disco display which you could not see was activated. 24 amp hours a day will kill the batteries in a few days. If left on a month by accident, the batteries probably will be ruined and will not recharge properly, ever.
So, the problem Airstream faces is what to do? They are using a car radio in an application it was not designed for.
My solution is to put a switch on the radio so I can be sure that all power is shut off to both wires, and even if the U/S switch is accidentally or deliberately turned on there will be no detrimental affects. The downside is that the station memory is always removed, and that I have to reset the disco lights to off when I do want to use the radio. So, I have to remember how to do that, and as you know, it is not an intuitive process.
I hope this helps in understanding the Pioneer Radio dilemma. I am sure the Sony is similar. There is just no easy work around in this case, for Airstream or the Airstream owner.