It's been done by hand in China. Not sure if we can replicate that in the west though.
Wage costs I'm sure would be an issue. Sounds like a crazy idea, but can't we just stop using pesticides that have provably been shown to harm a critical part of our food chain? I don't particularly care if Bayer loses profit, or if I have to pay a more realistic price for fruit and veg.
We could, but there is money lost in the process. Both for the people who produce, but also consumers. This needs regulation to become a reality.