Seems like Waze needs to authenticate devices better on their network. Don't allow anonymous users access to things like other users' data. Force people to have an account if they want the social media aspects. Those can obviously be made in bulk but the introduction of a captcha system would help prevent that.

Also, they need to anonymize the surrounding users. Describe a nearby user by their personalized icon but nothing else. This way, you can still show off the avatar but since the avatars are picked from a set list, you don't actually know who is who assuming the icon isn't too rare.