You've probably downloaded it previously (maybe on an old device) which is why it was so simple. I started using Google pay recently (as I'd gone shopping without my wallet), and when I downloaded it on my phone, my old bank card, which expired in 2017 was already on it. I don't for the life of me remember previously setting it up, but I must have at some point. It made adding my new bank card (and subsequently my season ticket) the proverbial 'piece of p!ss'.
You dont have to download your credit card details to allow download of the season ticket. (I have no trust in having a credit card on my phone, but my season tickets went into google play just fine.
I’ll take my card too. I don’t see why a screenshot wouldn’t as it’s just scanning a QR code but we’ll see. Might try adding a bank card to Apple Pay and see if that makes it easier if something is already on there. I use another app to store all my store loyalty cards on and I’ve put it on there by scanning the QR code. It looks dodgy if anyone looked at the screen (as it’s literally just the QR code on a white background but as that stores all the information that should work too in theory, it does for Boots, Subway, IKEA etc. and is a really easy way to have around all the cards with me without having to carry and sort through them all or have 20 different apps.