Busan Station is a circular building. On a high platform, there are duty-free shops inside. Of course, there are also convenience stores in the hotel. It is not checked by train in Korea. It is an open platform. It is directly on the bus. There is no one checking the ticket on the way from Busan to Seoul. There are not many people on the train. If you don't stand, maybe it's because of this that you don't need to check the ticket.