Right demographic mindset, bike-friendly transportation planning, cost, distance to intended location, cost, ROI, cool-factor, safety concerns, cost, in no particular order.
Cars are a constant threat...have you ever taken the time to look at drivers to see how many of them are actively on their phones ALL THE TIME? Literally watching YouTube, reading news, texting, Instagram, Twitter, you name it. I've had three accidents personally in the past year and a half since using Pikachu all the time, two because they pulled out of a cross street not anticipating my speed correctly, and one who cut across two lanes of traffic when he overshot the entry into a parking lot, again not anticipating my speed, and a TON of close calls with distracted drivers not noticing me despite a 290 lumen rear LED that flashes red/blue like cop lights, and a flashing 1200 lumen front flood. I now wear a helmet cam at all times in case of insurance involvement when it no doubt happens again.
I talked with an engineer from Intel about an AI project they're working on for object identification and long distance preemptive collision warning on motorcycles where it charts the trajectory of other objects from long distances in relation to the user...sounds like it could be applied to ebikes as early-warning for cars slowly drifting right too much (smartphone/distracted driver case) that would be far more effective than a mirror. I'm trying to convince him to let me be a guinea pig.