Why buy high-speed rail tickets online and send text messages to "paper tickets"?

Hello, I am also a student. To buy student tickets online, you must change them at the Internet window of the railway station. You must bring your ID card and student ID card. If you buy an adult ticket, you can exchange it at the ticket vending machine. Be sure to go to the railway station early to change tickets, because sometimes it takes some time to queue up. If you are afraid of queuing up at that time, you can change tickets at the ticket office, but there is a handling fee, but it is insurance. . . . Good luck with your car. Are you going home? Have a holiday so early