Why the need for a permanent Internet connection ?

For sure the developers of this application are not actually traveling the Thalys. The application needs a permanent Internet connection, as it cant store the actual tickets. So if you need to show your ticket to the controller and are out of a connection, well to bad for you. You need to constantly enter your password (it doesnt remember it), theres no Touch ID support, no iPhone 6 resolution support, no iPad support.

Digital Fury about Thalys - International trains