These are beautiful photographs, and the destruction of them is criminal. Everyone is right in that this is increasing again, thinking they have 'permission' to do this.
Here in Albuquerque, the city spent $30,000 to to paint a crosswalk for the Pride celebration here. Two days after it was finished, a group of motorcyclists burned rubber over it, defacing it permanently.
Fortunately there were plenty of security cameras that caught it and were able to catch the incident, and they were able to make arrests. The Mayor said that they will be prosecuted to the fullest extent of the law.
I know this sounds like a lot of money for a crosswalk, but normal white line ones cost $10,000 and only last 3-4 years. This one used highway paint and will last 10 yrs. There were lots of donations to have it repaired.