I do not use MUP’s and I have a bell that I ping when I pass. That’s just me and how I ride. SoCal is so densely populated now , when you are out riding , you get what you get. I try not to let it get to me . Some riders know how to ride and be safe, others are just ignorant or don’t care. That’s life in the city, try to focus on the good and hope for the best. Enjoy the ride!