The problem here is more of a supply / demand thing which you can't simply ignore that because the issue will never go away so long as the incentives for it exist.
If farmers paid good wages they wouldn't need to rely on foreign labour and food prices would go up. This is a workable solution, but is is what people living in western countries want?
We have the same issue here in the UK with the NHS.. We pay NHS workers terrible wages so we need to import foreign labour because wages aren't high enough to attract domestic workers. In one sense it's great because we get better health care than we would otherwise afford and foreigners have an opportunity to get better pay in the UK (even if it's bad by UK standards).
I've found many people here get angry about what we pay NHS workers while also getting angry about NHS waiting times. If we wanted to we could increase wages which would either require resource cuts and lower output or higher taxes for the same level of care. It would also mean we wouldn't need to depend on foreign labour, but who benefits from this? By paying more foreigners now have less opportunity to move to the UK and British citizens have sub-par / higher cost health care.
Presumably, it's the same with agricultural workers. Sure you can pay more, but who benefits from it? The root "problem" is that labour is extremely cheap outside of developed countries. Developed countries can cut themselves off from that labour supply if they like, but I have no idea what the economic incentive (or benefit) of doing so is for either the workers or the citizens. Call it modern-day slavery if you like but these are consensual working relationships, which presumably wouldn't take place if they didn't benefit both the worker and the employer.
So long as labour remains cheap outside of the developed world a trade off will always exist – paying more will just mean higher prices for citizens and fewer opportunities for those living in the poorest parts of the world, but on the up side you can say you pay a fairer wage by your own national standards.