>considering that it considered fake SMS train tickets to be document fraud, even though the law text never explicitly mentions text messages
That has nothing to do with the medium of the ticket and is all about knowingly presenting a fake ticket. The ticket is a document proving your payment for travel. They could be lumps of dirt and it would still be document fraud to present a fake hand of dirt.
Except the Supreme Court deemed the case to be of a principal nature, and granted relieve (i.e. no cost to either party), since it was disputed whether a fake SMS train ticket counted as document fraud.
That has nothing to do with the medium of the ticket and is all about knowingly presenting a fake ticket. The ticket is a document proving your payment for travel. They could be lumps of dirt and it would still be document fraud to present a fake hand of dirt.