Honolulu has placed plainclothes police on corners in Waikiki to catch jaywalkers. If this were about safety, they'd just have a uniformed policeman there to stop them. Just more revenue enhancement.
I think it's about the psychology of the thing. If you announce that there will be plainclothes officers at the streetcorner, and ensure that the word is out, you don't really have to deploy them to reduce the incidence of jaywalking. An occassional arrest is sufficient to convince the people that the threat is real. They don't know when they're being watched and when they're not, so the overall incidence should decline. If you use uniformed officers, the perpetrators know when they can get by with jaywalking and when they can't, and you have expend a greater amount of manpower to achieve a real reduction in jaywalking.
Cameras won't work with jaywalkers the way they do with red-light running, since pedestrians don't have license plates, or name badges. Most people will assume that their identity won't be known by the police, especially in a place with a large transient population such as Hononlulu's.