Article 1, Section 8, Clause 3 of the U.S. Constitution grants Congress the power to “Regulate Commerce with foreign Nations, and among the several States”. If farmers in Kansas feel they’re being unfairly treated by any company that trades across state lines their only point of recourse is their congressional representatives.
As a historical example, railroad companies were once notorious for business practices that unduly favored high-volume users. They'd provide discounts to large corporations while excluding small businesses, and they'd charge more for short hauls than they did for long hauls[0]. It was incredibly unpopular for years, and it disincentivized trade and development in perfectly suitable states like Kansas.
Yet it still took congress years to take action for the same reason it does today (they don't want to anger corporate interests). It finally took a politician from a populous state (Illinois) to bring the issue to bear and incentivize congress to act. It's not a perfect example of what you were asking for, but it's an interesting case study. Kansas would've been much less equally represented in congress than it is today. If anything, it's closer to being over-represented now due to the caps.
At any rate, and to your point, the result was the creation of the first independent federal regulatory agency, the Interstate Commerce Commission. Now there are at least 32[1]. This is often cited as an example of federal overreach. It's worth considering that without these agencies, however, that congress may simply be gridlocked on more and more issues the way they were on railroads for years even with more equal representation.
Despite any personal political views I may hold or knowledge I may have acquired, I get extremely nervous when people are quickly and passionately in favor of something like eliminating the electoral college. It's a challenge to find pure functions in our system. Ultimately, I have no grand conclusions to offer up here. I just hope you find it interesting or helpful.
[0] https://www.senate.gov/artandhistory/history/minute/Intersta...
[1] https://en.wikipedia.org/wiki/Independent_agencies_of_the_Un...