Absolutely we should expect them to solve easy/valuable problems first. Maybe that's fancy organic vegetables in a greenhouse, which certainly sounds much easier than 5-foot weeds growing in a thousand acres of deep mud!
But we farmed for a long time before inventing weedkiller. First by recognising weeds & pulling them out. Later by plowing, which is really just substituting mechanical work (from oxen) for human labor (and smarts). I don't see a fundamental reason that robot-weeding couldn't ultimately replace most chemicals & most plowing, but obviously not next year.
But there are a lot of crops, vegetables mostly, that are hand weeded. It's going to replace a lot of migrant labor. The main reason it won't replace herbicides will be cost. I'm not even certain that it would make economic sense right now for organically grown corn and soybeans.
There also may be problems with it in the Midwest. In California they turn on the water when they need it. What happens if it rains for three weeks in Illinois and the machine can't enter the field? Will it be able to remove fifteen inch tall weeds as easily as those a quarter inch tall? How fast will it operate under those conditions? If I have 2500 acres in that situation the weeds might be five feet tall by the time the machine gets to the last fields.
But if someone makes a successful business of commercial weed removal then like all tech the cost will come down over time, perhaps opening up the much wider market.