Paper certs vs. digital logs, which one holds up on a site like this?

Last week on a job in Gary, Indiana, the general contractor's inspector wanted to see our weld certs, and I handed him a binder from 3 years ago. He seemed happier with that than the digital records I pulled up on my phone, called the PDFs "easy to doctor" or something like that. But my crew's younger guys swear by the tablet setup, say it saves time on the daily reports and flagging repairs. I get the appeal of a paper trail when the Wi-Fi drops or a battery dies, but digital is way faster when you're chasing 40 welds before end of shift. Which one do you trust when a client is breathing down your neck, the old folder or the file app?