Speaking as a police officer (who has never written a ticket to a cyclist, BTW), I would say that there seems to be a general ignorance of traffic laws on the part of cyclists, or as well an attitude that as a cyclist they can freely disregard laws they find inconvenient.
Truth to tell, traffic enforcement directed at cyclists is rare, as they are involved in very few accidents proportionately, and when they are they are frequently the only casualty.
Still, in most states cyclists are subject to the same laws that are any other vehicle operator, and it's the opinion of various safety "authorities" that cyclists do best in traffic when they act like other vehicles. Gaining respect, as it were.
Also, it's well to bear in mind that though enforcement is rare, your insurance company will certainly perk up if they find that your accident was the result of illegal behavior on your part.
For myself, I think that cyclists riding in traffic should make an effort to obey the law. What does it cost?