Well, for me the reason is this, I can walk the edge of a field, and as I go, I can quickly set snares on each of the rabbit runs that I pass, I can do it almost without thinking, can have my mind on other things like the scenery, or birds/animals etc.. its easy. And come the morning, its once again easy, to find and lift the snares and take the rabbits away.
If I was to snare the holes, id be trapsing through brambles, crawling under pine trees, climbing fences, taring my clothes on thorns! I'd be in fecking ribbons, and I would have to cover ALL the holes so that I could sleep at night,