Well what I think is that police could get paid for successful kills and stuff, as someone mentioned above; but a wage to pilots is not possible, why?
Well, there was a time when mining was not very profitable, so everyone powertraded; then mining was made profitable again and a bunch of traders dissapeared, at the end mining was nerfed a bit so there is now a balance of traders and miner. My point is that people will look to the way they can earn the most money in a given time, in order to really give an incentive to pilots to fly their police ships, and earn money at the same time, police pilots would need to be paid at least 40 million credits per hour, to make it more attractive than mining/trading, otherwise when they need money they will just switch to their miners. If you have 10 police pilots patrolling that would mean 300 million per hour, there's now way to get so much money. That's the reason (according to me) that a wage is not possible.