The trend was allegedly started by Ward Clapham, now a 28 year retired veteran of the Royal Canadian Mounted Police in Richmond, British Columbia. During his time as a police officer, Clapham had the philosophy that every important breakthrough requires a change in the practices, mindsets, and principles that tie people to the current way of life. 

As he wrote in his book series Breaking With the Law, Clapham discovered the best way to make an important breakthrough in keeping the peace was by not doing things he felt were ineffective and unproductive. He had the idea of cops catching kids for doing things right. This idea developed into Positive Tickets. 

Clapham thought it made sense for police officers to be seeking out the positive things they see and rewarding the people who do them, instead of focusing on catching people doing things wrong and punishing them. In theory, it makes sense. 

Rewarding people for doing good things has been proven to be a better incentive to stay on good behavior than punishing people for doing bad. The idea spread like wildfire, and hundreds of thousands of these Positive Tickets have been handed out. 

Clapham is now assisting organizations in ways to reward and recognize employees and customers who behave well. 

(Source)