Why? Because it works! The city is - in spite of the continuing outbreaks of spamming - definitely cleaner today than before. I drive through areas of town that I used to frequent for business reasons and spot nary a sign where formerly they were weekly if not daily appearances. I drive through others parts of Metro Denver and see gratifyingly sharked new signs - I have my own distinctive swoop cut and these others are sporting similarly unique cutting patterns. Thus one of CAUSS's goals, i.e. teaching others how to shark, is clearly working.
Now, as to the municipalities' attitude toward street spam - I couldn't agree more. There seems to be little committment to keeping the stuff suppressed. My model community is Scottsdale and perhaps Phoenix, too. You never see the stuff on poles or roadside stickers. You got a yardsale, you make a paper sign, tape it to a cardboard box with a brick in it and put it on a street corner -FOR THE DURATION OF THE SALE. Once it's over, you better get it the hell out of sight! Municipal code in action. Effective. How about we start getting on our local politicians? What about asking the code enforcement people what the public can do to put some teeth into existing ordinances or getting effective ones adopted?
There are additrional ways to educate the public. The link below shows one which was exposed to 40,000 people this past summer.