So...strimmers

Most mornings I wake up to an irregular loud engine noise. It is not a constant engine, like a car running, and at first I thought it was a motorbike revving. I discovered it was one of these... So my initial thought process on most mornings goes like this: Did I sleep on the freeway? Did I join a gang of Bikers? Why is someone using one of these so early? Why do they need to undertake this job every other day? Are they being deliberately spiteful? Why on earth is it called a "Weed Wacker" when it is clearly a "Strimmer"?