These so called room cafes also exist in Japan where they are called Manga Cafes. They largely provide a cheap place to stay for people who miss the last train home from work. In South Korea it appears they have become very popular with minors:
A growing number of “room cafes” that do not comply with regulations has sparked debate on teenagers’ sexual activities ― a taboo subject in Korea ― after the government vowed to crackdown on these facilities where underage students were found to be having sex.
Korea Times
Room cafes, which began appearing in the early 2000s, offer a private space with basic amenities to visitors. But in recent years, many of these establishments have evolved into hotel-like facilities.
Unlike the past, when curtains or partitions were installed to offer privacy, some cafes now provide separate rooms with lockable doors. Many rooms are also equipped with a screen, bed and even a bathroom in some cases.
Although these room cafes look no different from motels or DVD rooms ― where minors are prohibited from entering under the Youth Protection Act ― these facilities have been able to circumvent the law, as they are registered under general business or restaurant licenses.
As an increasing number of teenagers have been found to be drinking alcohol, smoking cigarettes and having sexual intercourse at these facilities, the Ministry of Gender Equality and Family has been urging local governments and the police to launch a crackdown on “illegal” room cafes.
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