Was ist hier los? An der Station Dongdaemun History & Culture Park

According to the Korean welfare policy, old people get free ticket. Then the old people pay a small amount of money and use the subway to provide delivery services.

Those who are versed with this particular phenomenon, is DDP station the only hotbed of the „delivery service?“ Or should I expect stations in the middle of the map with a lot of transfer lines going through it to have the same thing happening?