Upon entering the chat room on the instant messaging app Kakao Talk, the first thing users see is a message promising that anyone who provides evidence of illegal acts by a certain airline may remain anonymous and won’t be publicly identified in any way.

The chat room has been set up by the tax office in the South Korean city of Incheon, the location of the country’s main airport, as part of an investigation into allegations of illegal smuggling of duty-free goods by the family that founded Hanjin Group, a conglomerate that began after the second world war that now owns Korean Air, a major airline.

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But instead of being a den for dime dropping, the chat is a mix of vitriol and despair over South Korea’s inequality, something the current government is working to address, and an interesting glimpse into current public sentiment.

Kakao Talk is the most popular smartphone app in South Korea, used by 92 per cent of smartphone users, so it makes sense that authorities would use it to seek tips from the public.

But a review of hundreds of messages sent in the chat room reveals little in the way of evidence. Instead, participants use the space to ridicule the investigative authorities and complain about South Korean officialdom’s inability, or unwillingness, to rein in the excesses of the country’s wealthy elite.

The smuggling allegations are the latest bit of bad press for the family, who have spurred public anger with behaviour seen as high-handed and belittling of underlings, seemingly sending the message that corporate bigwigs need not follow the laws and standards of moral decorum that regular South Koreans are subject to.

The family first became widely known outside South Korea in 2014 when Cho Hyun-ah, daughter of Hanjin Chairman Cho Yang-ho, threw a tantrum on a flight departing from New York. Cho was reportedly angry at how the flight’s cabin manager served her macadamia nuts – in an unopened bag instead of on a plate – and berated him before forcing the flight to return to the gate so he could get off.

More recently, Hyun-ah’s younger sister, Hyun-min, was accused of throwing a glass of water into the face of an advertising agency manager during a meeting. Both sisters were stripped of their positions in the company. Prosecutors are investigating Hyun-min’s case, and she could face charges soon.

That isn’t all. Adding fuel to the fire is a video, unearthed by a local broadcaster last week, that appears to show the mother of the two sisters violently berating a group of construction workers.

South Korean citizens being encouraged to rat each other out is nothing new. The government has long maintained systems of incentives for people to come forward with evidence of illegal acts by others, sometimes offering monetary payments in exchange for information.

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Some chat-room participants are of the opinion that the tax authorities are themselves complicit in the alleged smuggling, having failed to properly enforce regulations and monitor what is coming into the country. “Tax service is the problem. Related officials from there need to be held responsible. If they hadn’t obscured the facts, this case never would have come to this point,” wrote one user.

Others argued that it was pointless to trust the government to effectively investigate the case, with one writing, “If you have evidence, send it to the media instead of the government. They’re more trustworthy.”

In one sign of public discontent with the family, thousands have signed a petition with the presidential office asking that the word “Korean” be removed from the company name, on the premise that the company isn’t fit to represent the country internationally.

Another repeated theme in the chat room is disillusionment with the excesses of the families that run the chaebol, the sprawling conglomerates that dominate the economy. In the past, chaebol brass have been accused of misdeeds, including unfair business practices and tax evasion, but often get off with lenient sentences or pardons.

“In our country if you’re president you can get caught. If you’re big business you won’t get caught,” one user wrote, an apparent reference to the case of former President Park Geun-hye who was impeached last year and in April was sentenced to 30 years in prison for abuse of power.

Park’s conviction assuaged some public anger over corruption, and President Moon Jae-in has vowed measures to even the economic playing field. “Moon should seek to distance the state from too close ties with industry – part of his job is signalling to the public that the state doesn’t serve at the pleasure of business – and to support policy reforms which loosen the stranglehold conglomerates have over suppliers and small and medium-sized enterprises,” said Steven Denney, a Graduate Fellow at the Asian Institute at the University of Toronto and specialist on South Korean politics.

And the corporate titans still have defenders who argue that they are too important to the economy to have their size or strength eroded. An editorial in the pro-business Maeil Business Newspaper argued for a need to tighten airport customs procedures to prevent smuggling, but said nothing about the Cho family conducting themselves with more care or compassion.

Last Friday, dozens of Korean Air employees held a rally in central Seoul, calling on the Cho family to step aside from management of the airline. Keeping with the theme of anonymity, participants wore Guy Fawkes masks as they waved placards and chanted slogans.

The main organiser of the gathering was Park Chang-jin, the cabin manager booted off the plane by Cho Hyun-ah in 2014, who is still working for the company and still struggling with the public humiliation. He says the Cho family’s behaviour has garnered so much attention because it draws attention to unfairness at the core of South Korean society. “We’re all taught that if we’re diligent and follow the rules of the country, the country will protect us. But I realised that there is no system of support for people like me,” Park said. “I just hope that by speaking out about my case, I can be part of a change of our society’s values.”