The reason the Texas hog problem took off according to my wildlife mgmt friends is thus. Deer lease prices took off several years ago and the leases want something else to hunt for the money, so ranchers started trapping hogs and relocating them so that the hunters could come year round to hunt. It had gotten so bad that the TX legs. passed a law that it was illegal to have a live feral hog in a trailer on the highway unless it was going to a slaughter facility.
