You sure that pirates get paid more by doing higher priority jobs then ones with lower priority jobs? I thought the priority was just in which buildings would get assigned workers first. I didn't think it actually forced me to pay higher wages to pirates!Manual Page 26:Pirate Workers
Pirates are generally a lazy bunch when not at sea, but they will take some land jobs if they cannot find a job on a ship. After all, they have drinking and wenching habits to support.Pirate jobs are of two types: overseer and guard.
For an example of a guard-type building, click on a watchtower or on your palace. For an example of an overseer-type building, click on a farm. Guards are the only type of worker in their buildings, while overseers work with captives in the same building. Using the 'priority' menu below the worker area sets the pay levels for pirates who take these jobs.
On your island, only pirates receive pay. Captives never receive money from your treasury.