It's probably not a lack of desire to enforce the laws so much as it is difficult to catch the perpetrators.
Catching, selling and relocating wild hogs is big business. The so called "game ranches" pay good prices for wild hogs. Some of these "game ranches" also buy domestic hogs.
Short of mass poisoning; trapping is the most effective way of killing hogs. Yeah, you can shoot them from helicopters: The rental rate for a one hunter copter is about $600 per hour.
Biggest problem is with the state game commissions; they're afraid someone will poach a deer. Here in OK we are not allowed to hunt wild hogs at night: In theory, a farmer or rancher can get a permit from the game warden to hunt hogs at night but few bother. We are not allowed to hunt wild hogs with centerfire rifles in the WMAs outside of deer season. Then the game commission turns around and hires helicopters at $3,000-$,4000 per hour and shoots wild hogs in the WMAs.