The cartels are also extorting avocado farmers for a cut of their profits. It turns out that, if you have a lot of bad people in power, they find ways to do bad things for personal enrichment.
Corruption is rife. Every single transaction you make in an economy contains a percentage of evil (example: surely you disagree with some of what your government does): how did you decide that avocados are beyond your limit and carrots are not?
With the price of avocados pushing higher and higher, I think there is too much money in avocado the avocado trade. Farming is basically limited to specific areas. Lowering demand (how ever small) is making a measurable change that I fell like I am contributing to. Voting with my dollars is the only true ways to make a change. As much as this might "hurt" the farmers, it is also hurting the cartel.