It's the easiest way to keep weeds under control but not the only practical way. (Source: I worked for the weed science department (yes, they had one at my school) while at university.)
Here are some other methods for reducing weeds:
1) Before planting, till and water the field causing weeds to germinate. Then harrow the field killing all the weeds. Do this multiple times if needed.
2) Good old fashioned cultivation as was done before the herbicide period. (The article on the robot was posted a few days ago and in response I posted the below... it has a lot of pictured of weed control devices which may be interesting to someone working on robotic weed control....https://archive.org/stream/SteelInTheField/Steel%20in%20the%...)
3) Crop spacing. Space crops so they out-compete the weeds (this is already usually done).
4) Keep fields clean. Keep the ditch-rows clean. Don't let weeds go to seed. After a period of time the bank of weed seeds in the soil is reduced and there are less weeds to control
I know herbicides are faster and cheaper (if we don't consider externalized costs). But they aren't the only "practical" way to eliminate weeds. It does take good management and more effort to eliminate or reduce herbicide use though. I personally think it's very worth it. Oh, and I'm excited about robotics. I don't know about this device, but I do think field robotics is the future.
I remember a crusty old guy in Florida showing me his watermelon field that was full of weeds. I said something about it and he said the weeds actually shaded the watermelons keeping them from sunburning and he had no intention of removing them. I don't know if this is necessarily true or if he just didn't feel like doing anything about it but apparently he didn't think the weeds were causing economic harm and there were a lot of watermelons in spite of the weeds.
For rice plantations, he does try to ensure weeds don't grow. I don't remember the exact methods advocated, but I believe it was placing straw all over the ground, and for some crop he grew clover in the downtime between harvest season and growing season, I think. I don't recall too much, though.
One of the main crops I was doing it for was squash. The squash plant is pretty broad and the hand hoe allowed you to get close in under the plant. That's something this technique couldn't handle.
As someone working on minimum wage, I could get through a pretty large area in a day. Sometimes there would half a dozen of us in a gang. I'm not sure how much a device like this would eventually cost but I suspect for the same money you could buy a lot of minimum wage manual labour.
Either way, cool prototype!
I'm not so sure punching is a great solution though. Weed is incredibly good at reforming from very very small bits left standing.
Then you could use that video to train a network to find weeds and get rid of the operator. You could also test the network a part of the same dataset to see how well it finds the right spots.
Possibly locked review: http://link.springer.com/chapter/10.1007%2F978-3-642-13145-5...
This works with a chemical - i.e. an accidental low dose, but I don't see how that would happen with this machine.
If, you had a weed that was so close to the crop it was only sometimes recognized then yes, but weeds mostly look nothing at all like the crop.
Seriously though, you're right, even if it requires a human in the loop it's still a huge benefit. Farms could even use remote workers to do the identification.
I wonder how the performance of plant recognition degrades over the course of the crop cycle, if at all. We see in the video that some leaf matter remains after the weed is driven into the ground, and this leftover matter will influence classification during the robot's next pass. Unless the leaf matter is removed between passes it will accumulate throughout the crop cycle.
In  the researchers note that one reason they chose to deal with seedlings is that there is relatively little plant leaf occlusion at that stage. In  an end user is relied on to take a photo with a light, untextured, background and does not at all deal with partial plant leaf occlusion. That paper is not applicable to the uncontrolled field scenario.
I also found  while writing this comment, but have yet to read it. It boasts even better results (>90% correct for corn, 73.1% correct for tomatoes in an uncontrolled setting)than 
The ones they actually used were the "Harrison Transplanter".. could not find a video, but here is one http://bid.sheridanauctionservice.com/images/lot/3471/347193...
Harrison is neighbor of ours who worked at Brookhaven National Labs but then became an entrepreneur. He sold a bunch of them.
...now make one that mounts on a front 3pt hitch and you might actually sell one.
No need for a special robot when a different piece of equipment with its own power source has to go down the field anyway
If large companies can figure out how to house innovation, it would solve some major problems that they have. But our current model of management is basically inimical to true innovation, so personally I'm skeptical.
Why garden when your neighbors will have amazing gardens cheaply designed and looked after by robots.
And it'll be smart, it'll know exactly how many weeds to leave so it doesn't look to perfect, exactly when to plant and pollinate, order things online when needed.
To take your point literally
Like jobs, at first it's great, highways, planes, easy to access information open up the world to everyone.
But it'll get to the stage where it's too easy. Adventures are getting harder to have. You no longer find that amazing restaurants, you yelp them and book months in advance.
In the future when you're chatting to someone about visiting county X and you realise they have only been there virtually it'll perhaps devalue your own journey, then perhaps you'll get what I mean.
What about using a laser to destroy the weeds?
The robot in the article just pushed the weed underground a few inches. I imagine that some weeds would just pop back after a week, and that the robot would just punch them down again.
Around here, we have an invasive species called scotch broom. If you cut off the plant at ground level, it will grow back. But if you cut it off after it flowers, it'll die. Mowing it flat regularly will also kill it.
At very low power, not enough power to kill a plant that has lots of water in it.
While you're at it, attach it into a drone. Useful for animal herding and crowd control as well.
Because outside of a lab, lasers with enough power to zap and destroy 100 plants per second don't actually exist?
(Not that I've done the math, but you really do need a lot of power.)
Lasers, especially fast ones will only handle superficial stuff.
Let me know if I should elaborate further and make an Ask HN out of this?
On the hobby side, check out farmbot http://farmbot.io/
Grass where it serves some benefit such as a backyard at least serves a purpose. Front lawns in locations where they are ornamental are a blight.
Townhouses don't have lawns:
And they're excellent building blocks of walkable neighborhoods.
How very kind of you to epitomize the "get off my lawn" meme, but I'm not on your lawn. I'm not telling you to get rid of your lawn, but the concept as it exists now and it's popularization is at best wasteful, and in some cases actively causes problems with water availability in some areas. Some reform in the popularized concept of a front lawn would be beneficial to everyone.
I get having a lawn in a desert is a poor use of water, but for many houses and recreational areas, it's an excellent way to cover ground.