Horns do one of two things, it will either make them stop, or initiate the automatic reflex of the middle digit on the free hand extending, gesturing what the driver thinks about your horn honking. I am of a mind that while it is important to make your presence known (to the unaware) a visual is better than an audible. Naturally, this only goes so far. Being prepared for the unexpected is something two wheel riders can to to protect themselves. How,??? Protective equipment, riding jackets, knee and shin guards, helmet, gloves and boots. Reflective tape strips are usually sewn into most of the fabric jackets. When I was a kid, my grandmothers favorite saying was, "Children should be seen and not heard". I was pretty rambunctious when I was six. The same is a good motto for bikers as well. Don't get me wrong, a loud horn is effective and I am thoroughly convinced that loud pipes can and do save lives.
I am so sorry your scooter was trashed by someone preoccupied with their personal life they had to put yours in jeopardy. Cell phones do have a place while driving, and that is in your pocket. Bluetooth is better, but still a distraction.
Bottom line: a two wheel rider must always be on their guard and prepared to react to the situation at hand.