For whatever reason apple required passes to be digitally signed with an apple developer certificate. On the other hand a screenshot/pdf is "good enough" that they didn't bother fixing it.
> For whatever reason apple required passes to be digitally signed with an apple developer certificate
Apple uses every opportunity to try to increase developer and user lock in. This was no exception. I see this new move as begrudgingly opening the doors to all as not enough people were signing with Apple Developer Certificates.
Unfortunately, they're not even good at it. Setting up a custom CI chain today as a brand-new member of the Apple Developer program, I found out that they have at least 9 different certificates to generate with no explanation which one you need on the page, and after I had generated one, downloaded it, and imported it into the keychain, the certificate was invalid. I additionally had to go to some cryptic looking page[1] and manually download the "right" in intermediary certificates.
QR code definitely in focus, lighting good, the screen will brighten automatically for maximum contrast, and it will be in an easy-to-find location (especially handy if location services knows you are near where you need the pass and suggests it automatically).
You can double tap the lock button to open your wallet with all your passes. Also it automatically raises the brightness for QR passes to make it easier for readers.
You could do the same thing with shortcuts I guess but using the first class feature is nice.