I grew up with back tags as the norm, here in Ohio. They just did away with them a few years ago. (I don't recall exactly when). The only problem I recall with them, was remembering to move them to whatever coat you were to wear. Running the pin through the edge of the collar was fine with every game warden I ever met, so there was no need to damage the coat, though hunting coats were made with the hemmed holes already in place. I know, my rabbit hunting coat has them still.
I can't say they really do anything for or against poaching, but it did allow a game warden to glass you from the road to look for that flag of color, and if the wrong color was showing, he would check your tags. Otherwise, he didn't need to mess with your hunt.
Sometimes, guys would have ten years or more of tags in that holder, and sometimes the wrong one was showing in the window.
Nowadays, I carry my hunting permit in my wallet, like a concealed weapon, to show if needed. While a back tag was a declaration, loud and proud " I am a Hunter!". I still have mine, though it has not been required for years, But I hang onto it. Like a badge of office, now retired. It reminds me of my early hunting days, as a boy, walking the fields with my father.
The only real difference between a good tracker and a bad tracker is observation. All the same data is present for both. The rest is understanding what you are seeing.