As someone who has been involved with professional laser shows for over 23 years, I really annoys me what some of these "t**ts with laser pointers get up to. I have performed many outdoor laser shows, with large frame argon lasers of up to 12 watts and 7KW Xenon searchlights. However these were carefully staged events.
As a requirement we had to notify the CAA (AUS dept) a minimum to 28 days prior to the show to allow for suitable warning notices to be issued. Failure to do so was in contravention of articles 63 & 110 of the Air Navigation order 2000 and carries an unlimited fine.
These people are also contravening local government H & S laws. It is Illegal to perform a "public show" without the approval of the local Environmental Health officer. Technically, speaking these are "public shows", as they are visible to all. There are plenty of laws to stop these kids, usually its trying to catch them that is the problem.
PS I wouldnt worry too much about blue lasers, thet are even less visible to the eye than red ones are (about 1/4 for the same power) and are still quite expensive to purchase.