Poison is convenient. For one thing, it's effective even without any effort or skill. Setting an old-fashioned trap is not hard, but it does take a bit of practice to get the sensitivity just right. I've known lots of people who set theirs so that they wouldn't trigger for anything smaller than a capybara, watched their bait get stolen a couple of times, and then gave up. Also, the very same feature of knowing whether you caught something also means you have to see it and dispose of it. I have no problem with any of this, but many people do. Usually they only find out about poison's down sides when it's too late.

BTW some of the older poisons advertised that victims would actively seek to get outside before they died, which would avoid the "died in the wall" problem. Such claims might or might not have been true, but people continue to believe that for all poisons.