Wars, supply-chain disruptions and inflation became familiar explanations every time prices climbed.
Now, a wave of antitrust investigations suggests another force was also at work much closer to home.
Regulators say some of the country's biggest food and fuel suppliers had been coordinating prices instead of competing, helping keep household bills elevated even as global commodity costs eased.
The latest and largest case came on July 7, when the Korea Fair Trade Commission imposed a record 747.57 billion won ($501.5 million) fine on four dominant producers of starch and starch sugar — Daesang, Sajo CPK, Samyang and CJ CheilJedang.
According to the regulator, the companies colluded on the timing and scale of price increases 13 times between May 2018 and October 2025. They not only agreed on when prices would rise but synchronized customer notification letters and even visited post offices together to confirm the notices had been mailed.
The penalty eclipsed the previous record of 671 billion won imposed in May on seven flour millers, which itself surpassed the former record of 668.9 billion won levied against six liquefied petroleum gas suppliers in 2010.
Taken together, this year's enforcement actions against sugar, flour and starch-sugar producers amount to roughly 1.83 trillion won in fines, according to the Korea National Council of Consumer Organizations, making 2026 one of the most aggressive years ever for Korea's antitrust watchdog.
Nor has the crackdown stopped at supermarket shelves.
In May, the commission fined the Korea Layer Association for publishing benchmark egg prices that effectively guided producers to keep prices elevated despite stable production costs.
Earlier this month, prosecutors indicted the country's four largest oil refiners — HD Hyundai Oilbank, SK Energy, GS Caltex and S-Oil — over an alleged fuel price-fixing scheme that authorities say distorted competition worth roughly 26 trillion won in the aftermath of the U.S.-Iran conflict.
The breadth of the investigations points to a problem that extends well beyond isolated misconduct.
What makes this year's crackdown particularly striking is not merely its scale but its familiarity.
Many of the industries now under investigation have been caught before. Sugar producers were punished for collusion in 2005, flour millers in 2006 and LPG suppliers in 2010. Yet nearly two decades later, regulators say many of the same sectors slipped back into similar practices.
Consumer groups argue the consequences have been visible in household budgets for years.
The Korea National Council of Consumer Organizations estimates international wheat prices fell 15.2 percent between early 2022 and late 2025 while domestic flour prices rose 20.3 percent. During the same period, raw sugar prices increased just 7.8 percent, but retail sugar prices climbed 37 percent, widening the gap between production costs and what consumers ultimately paid for groceries and dining out.
Why does collusion keep resurfacing in these markets?
Economists point first to industrial structure.
Many of Korea's food ingredient industries are tightly concentrated, with only a handful of producers dominating national supply. Their products are largely standardized commodities with little room for differentiation, demand remains relatively stable regardless of price, and new entrants face high barriers to entry.
In such industries, economists say, the incentives to protect profit margins through coordination rather than competition can become difficult to resist, particularly during periods of volatile raw-material prices when customers are already expecting costs to rise.
President Lee Jae Myung has framed the issue as one of market integrity as much as consumer protection.
"Price-fixing that exploits market dominance is a cancerous element that blocks fair competition and undermines trust in the market," Lee said during a Cabinet meeting after recent enforcement actions.
The government now hopes to change the economics of collusion itself.
Until recently, critics argued many companies viewed administrative fines simply as another cost of doing business because the financial gains from coordinated pricing often exceeded the eventual penalties.
To reverse that calculation, the Korea Fair Trade Commission strengthened its penalty guidelines in April, raising minimum surcharge rates by as much as twentyfold in some categories.
"If a firm gains 30 percent and is sanctioned 15 percent, collusion cannot be stopped," KFTC Chairman Joo Byung-ki said, pledging to push for higher statutory penalty ceilings so illegal profits no longer outweigh the risks.
In the starch-sugar case, regulators went beyond imposing fines. The companies were ordered to restore prices to competitive levels and report all subsequent price adjustments twice a year for the next three years.
Not everyone believes harsher penalties alone will solve the problem.
Cho Dong-geun, professor emeritus of economics at Myongji University, said regulators should distinguish clearly between unlawful collusion and legitimate business communication while focusing more closely on whether coordination actually harmed consumers.
"Overcharging consumers is clearly wrong, but a certain degree of corporate freedom in business, including communication between firms, must also be recognized," Cho said.
For consumers, however, the issue remains straightforward.
Global wheat prices have retreated. Sugar prices have moderated. Supply chains have largely normalized since the pandemic. Yet grocery bills remain stubbornly high.
Whether this year's record-breaking penalties mark a genuine turning point will depend less on the size of the fines than on whether companies finally conclude that collusion costs more than it pays — and whether the next fall in raw-material prices is reflected not just in corporate balance sheets, but at the supermarket checkout.
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