Same reason why we have so many gun laws that mean the same, just in different words. Listen as an officer I honestly never knew of this law, but opening day of the 2003 shotgun season, it was about 5:30pm I was at my truck changing, my friend Sean was waiting for me on the side of the road ( about 70yds. away ) with his buck, Game Wardens pulled up, checked his licenses, and the tagged deer, then asked for his card, he told them he has one but left it home, Sean called out for me, I came over, ID myself to the two Game Wardens, I asked them whats the problem and they explained it to me, they gave professional courtesy to Sean thru me. Also this year hunt during the antlerless shotgun hunt, my friend Sammy and I came out of the woods, a different Game Warden pulled up, he saw my PBA shield in the window, asked me if I was on job, and I said yes. We started BSing, then I brought up about what happen a year before, and he said Yes that some wardens are checking for the cards.