content: lasers would be awesome, probably not practical but definitely awesome. i remember seeing a smaller roomba type weedwhacker a while back but you had to put barriers arround the plants you didnt want whacked. there's two issues i can think of though off the bat.with the autonomous mechanical weed killer bot 1. unless you destroy the root system most weeds will come back over and over again so on a 200 hectare plot you'd need a thousand weedwhackin laser bots running 24/7 and they'll no doubt break or hit a rock and get stuck on their back like a turtle and require more money and maintence and 2. 100 billion dollar industries dont take kindly to being put out of business so expect some false flag robot laser deaths to scare the public away from the new tech. other than that i like where your head is at.