Earlier this month a shocking scene played out at Panmunjom in the demilitarised zone between North and South Korea.

Ro Su-hui, the South Korean vice-chairman of the Reunification of the Fatherland Union, was returning from North Korea where he had paid his respects at ceremonies to mark the 100th day since the death of leader Kim Jong-Il. Before re-crossing the border to the South, he declared "Hurrah for the unification of the two Koreas!" to a cheering crowd and was presented with flowers by his hosts.

But as the grinning 69-year-old crossed the border, he received very different treatment by the South Korean border security. The watching North Koreans howled in horror as Ro Su-hui was thrown to the ground and carried off in a headlock.

The arrest made a very small splash in the western media, which comes as little surprise because a story with a warm North and a cold South is doesn't square easily with the message that has been delivered by media outlets in Europe and the US for the last two decades.

Reunification and conciliation are usually portrayed as South Korean concepts, while North Korea is seen as a closed state, hostile to such talk on "idealistic grounds" – a view perpetuated by media outlets' lack of interest in all recent North Korean initiatives. In fact it is almost impossible to find any piece of positive European journalism relating to the Democratic People's Republic of Korea (DPRK). The days of cold war pantomime journalism and great ideological battles might be over, but North Korea remains an area in which journalists have free licence for sensationalism and partiality.

The lack of western sources in North Korea has allowed the media to conjure up fantastic stories that enthrall readers but aren't grounded in hard fact. No attempt is made to see both sides of the Korean conflict: it is much easier and more palatable to a western audience to pigeonhole the DPRK as a dangerous maverick state ruled by a capricious dictator and South Korea as its long-suffering, patient neighbour.

These roles are dusted off whenever there are flare-ups, such as the Yeonpyeong Island incident of 2010 when North Korea was condemned for firing shots at South Korean military and civilians in an "unprovoked attack". It was not widely reported that South Korea had been test firing artillery in a patch of ocean that North Korea claims ownership of or that North Korea's repeated demands for an explanation were ignored. While military intervention may not have been wise, it was far from the random act of hostility it was made out to be.

When the South Korean navy ship, the Cheonan, sank on March 26, 2010, the South Koreans accused their neighbours of having fired a torpedo. A detailed rebuttal by North Korea's military was disregarded by the wider world, as was the offer to aid an open investigation.

One of the South Korean investigators, Shin Sang-cheol, sacrificed his career to express his belief that the Cheonan had run aground in a tragic accident and with reports of evidence tampering circulating, even the South Korean public wasn't widely convinced of North Korean involvement: a survey conducted in Seoul found less than 33% blamed the DPRK. Nonetheless North Korean guilt was stated as fact in the British press.

Since the bloody coup of 1979, South Korea seems to have had journalistic carte blanche as the "lesser of two evils". While North Korean actions are condemned and derided, very few column inches are devoted to scrutiny of South Korea's president Lee Myung-bak and his oppressive policies.

The National Security Act, of which Ro So-hui fell foul, gives the South Korean government the right to prosecute anyone speaking in favour of North Korea or communism in general. There are frequent reports of detention without trial, human rights abuses and clampdowns on freedom of speech. Both Koreas are quite justifiably scared of the other but when South Korea flexes its military muscles, the North is expected to watch passively with any attempt to do the same reported as an act of despicable brinkmanship.

Whatever your view on the actions of North and South Korea's governments, the hypocrisy of using one-sided journalism to label North Korea a rogue, propaganda-led state is surely self-evident and fans the fire of intolerance and animosity. The Korean divide is a complex, multi-faceted political situation. Nobody benefits from turning it into a moral melodrama and we should demand more from our supposedly impartial media.

• Follow Comment is free on Twitter @commentisfree