Have you ever been hunting? Because there are large portions of this country that are a real fucking bitch to get to and move around in, plus all the environmental risks. So for a lot of areas trapping and hunting is great and kill of most if not all the possums, meanwhile in the isolated dangerous to get to areas you're probably going to end up with little possum enclaves. Which is why 1080 is so great, because it's much easier to dump stuff from a helicopter then get their, set up a bunch of traps and shot a bunch of a possums. No one method is going to realistically eradicate possums, but a combination of methods has a much better chance since possums are crafty little shits that really don't like dying.

I don't see why we should not do anything just because it's not 100% effective, 1080 isn't 100% effective, trapping wont be and hunting wont be, but three 90% effective things is way better than going "Ohh it wont kill 'em all so what's the point then, better just let them keeping breeding and butchering our wild life, yes sirey so glad we didn't waste money on killing most of 'em what good would that do.