Maybe a lot of farmers don't want to drastically increase their herbicide use?
Maybe it has more the fact that humans are risk averse. We just don't want to make financial sacrificed in the short term to get longer term rewards. Many of us want to do good, but we also don't want our 401ks and subsidies to go down.
Edit: NVM, it was pointed out elsewhere that the needed equipment is different
When we as a civilization making decisions ending up where we are now (depleted soil and what else not looming). It does make one wonder if the current financial incentives is NOT aligned with the incentives of living beings on the planet? How can we make it so?
Where and when did that misalignment happened?