Hunting them is a pita. They're smart and cautious so if they think they're in danger they'll hide all day. They're strong and compact so they can push their way in to very dense brush where following them is a pita. Large groups will often scatter when disturbed, tanking off in every direction. It's time consuming, you need a lot of people and dogs, generally with thermal and night vision gear among other expensive kit, you have to cross fences and property lines which is a huge problem in america.

They do, and make big bank; but once you start you have no incentive to reduce the population as then you'd run out of pighunts to sell.