"Does this mean that we value kittens more than motorists?"
It depends who is doing the valuing, and in what circumstances. Imagine a person who is absolutely devoted to his/her dog, and is told that unfortunately there's only room on the lifeboat for either the dog or a complete stranger - one of them must die. What would the dog lover's response be?
Context matters a lot, and in the context you describe the reward for information about the concrete droppers is coming from Crimestoppers. The reward for the kitten killer is being offered by an animal charity and The Sun. The animal charity's motive is obvious, as is that of Crimestoppers, itself a charity. The sun's angle is as described in fourm member's earlier post.