Your receipt is sent by E-mail or text message and serves as your boarding pass, which you can print or show to the driver on your phone.

他们以电子邮件或者是短信的形式收到购票的收据，然后上车检票的时候将其打印出来或者直接将信息显示给司机就可以了。

youdao

In addition to letting users dedicate different tasks to different screens, Mr Martynov suggested users might want to display important information such as an airline boarding pass or a map on the e-ink screen to take advantage of the fact that the technology only uses power to refresh - and not maintain - its image.

BBC: Yota smartphone

If you think about it, printing out a boarding pass is almost as silly as printing out an e-mail.

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