I look at cars compulsively here in the US Pacific NW, and about 50% of the cars on our very crowded roads are Subarus, but I don't think I've seen the sticker. So it might have no particular connection to the car itself.
I have an idea. Get you some of these bad boys, put them on your car, laptops, whatever you carry in public. Eventually on of those SDS sticker people should come up to you and ask you why you hate SDS (and hopefully they’ll use the full name), and then you’ll know.