When you install a conventional tail light on the A-bike, you'll find that the light interfere with the folding. So you have to twist the light to the opposite side before folding the bike and twist it back after unfolding the bike. This additional step makes some people feel inconvenient.
Someone in Hong Kong has installed real lights on his A-bike by inserting LEDs directly into the back of the saddle which prevent the real lights from affecting the folding mechanism.
Here are the photos: