If a few vegetables providers start a venture with value proposition of providing parasite free veggies and become successful it can force the others to join the race.
This is an awesome strategy that will indeed change some minds and attitude of buyers. But it will likely lead to higher prices. At the end of the day, it help differentiate between thode customers that are out for quality rather than quantity.
It is a known fact that people would always want to go for cheaper things, especially in this part of the world. It is even a good proposition, because at the end of the day, when they false sick or get infected, they will obviously know it is as a result of their doings, since they clearly understand the implications of going for the cheaper unhygienically processed Vegetables.
Well even if such a venture can find fraction of customers who would pay for it, and show high profits other farmers will be pulled into the system. I am thinking more like when I was young, in India we used to drink ground water directly from pumps. In hill stations people drank it directly from rivers too. Then they slowly started injecting the concept of bottled water and aquagaurd came up with water filters for home. They were expensive to afford. But everyone wanted to give their children clean water and would somehow save for installing one. My father bought the filter too after he saw most of his friends and relatives getting them. And now in restaurants they would ask you - "sir bottled water or plain water". And even though plain water is free, most of the times we will go for bottles water. Now there so many companies who followed the lead of aquagaurd and bisleri. I think that clean food and clean water is such a basic need that it overrides the people desire to go for what is cheap. Obviously it depends on the larger economic situation of population, but it is still a very important need. If not by usual economics there are ways of getting people these needs by philanthropic fundings. BTW, I have a labmate from Nigeria, and he explained it to me the situation with the government there. So I think this is lot easier said than done of course.