What there really should be is a wallet equivalent of an ics file. It doesn't need to support everything, static images would be enough for most use cases. Advanced features could then require the current model.

But that would require collaboration, and standards, which seem to have gone away as smart phones came in.

W3C Verifiable Credentials [1] does almost exactly what you suggested and was recently approved as a top-level W3C standard. Adoption has been sluggish outside of digital identity (with Android [2] and the EU digital identity wallet being notable exceptions), but I think it is because the family of standards is relatively new.

[1] https://www.w3.org/TR/vc-overview/

[2] https://developer.android.com/identity/digital-credentials

This has existed since the first version, except it needs to be signed with a valid apple cert.

A .pkpass file is a zipped directory that has a json file and some assets. There's no need to have a more limited version, a pass is already very limited.

The issue is spoofing. Major event ticketers are unwilling to publish passes if there's nothing to stop someone else from publishing a pass that is indistinguishable from their's and thus is an avenue for fraud.

The difference with events is that an ics file is not something someone's going to try to sell you or that you'd want to buy. But anyway, all Apple would have to do is stop checking the signing.

This exists, .pkpass. You mostly don’t know about them because iOS tries to abstract away the file system, and because each one has to be code signed by a registered Apple Developer account.

Apple has .pkpass