Rude is one thing, in a big urban environment, they can be horrendously dangerous. At least a few times every month I see me or someone else almost plowed over by a driver making a turn with their eyes glued to their cell, obviously texting.

Nor can I take a bike ride without seeing someone ON a bike also not paying attention, either gabbing or terxting... EVEN on very narrow MUTs that are barely 3 bikers wide.