You didn't happen to use OpenDoc in the day did you? Did you meet Steve Jobs at a Q&A session?
Apple is a closed ecosystem. We all know this. Apple Wallet facilitates payment. It stores Credit Cards, Loyalty Cards, Membership Cards, Travel tickets and so on in a way it deems best. I wouldn't call it a mess because it doesn't do what you want and because it purposefully doesn't allow other companies to use it's IP (of which, it gets paid of course).
Apple Pay offers a direct service to the bank. Certainly in the UK, there is a piece of legislation called Section 75 which protects the card holder from companies going bust i.e. you pay for goods or services, company goes bust, Bank reimburses you. Paypal doesn't have this protection because it's an intermediary and doesn't deal directly with the bank - it has its own 'private' method of dealing with this sort of thing. Great when it works but you don't have the law on your side when it doesn't.
Finally, if you want open standards, Android is a major competitor well known for its open stance. The problem with open standards is that, like Windows, you need to keep support for older technologies and things don't get updated quickly enough due to the risk of breaking something. This is just Apple's way. You do have a choice.
No, I've always used Microsoft Office, and since the data is open due to the XML-based formats with the .x extensions, it's not a problem.
I must have done a poor job of explaining the issue.
You're confusing two things and overcomplicating it.
There's the payment platform and their protocols; they can be open or closed, and then you have the application endpoint itself.
I don't expect Apple not to have the right to create a closed payment platform (Apple Pay). They can do this all they like and have it interface with their Wallet app. ApplePay (the protocol) doesn't need to be open.
I expect the Wallet application to have an API to allow third parties to plug in and present their own cards within their App. Offering a single location to go to do what they need.
It's the same philosophy with the Home app and the change via the extension of the Matter protocol.
Before the Home App, users required a separate app to control the fan in the kitchen, another to control the different brand of fan in your bedroom, another for the security cameras, another for the aircon, etc. - Bad user experience.
So Apple created the Home app. A solution to be a single application to be the centre point for controlling Smart home devices. The catch? You needed to implement the HomeKit framework that had its own set of hardware requirements and pay Apple a fee. They later moved to opening up the HomeKit protocol to allow for unofficial device support. And the world of Homebridge was born. - Awesome.
Fast forward a few years, and the Home app added support for, Matter (a 3rd party protocol), thereby adding support for even more IoT/Smart home devices which didn't commit to HomeKit.
The Wallet app should have followed the same design principles.
Soon I'm going to end up with seven different app market stores to download the apps I use and hunt through eleven different wallet apps to find the card I need, while I hold up everyone in queue.
This is a bad user experience intentionally put in place for profit.
Apple is going through what Microsoft was forced to do 15 years ago and open things up by court order.
Of course, Apple can develop its own platforms for different solutions and go on to license out for profit, while allowing its OS and native applications to offer support for 3rd party solutions integration.
The EU is forcing Apple to open up parts of the platform, but Apple chooses to make it hard for 3rd parties to implement streamlined solutions in Apples iOS applications.
As you said, Apple Wallet currently supports credit cards, loyalty cards, membership cards, travel tickets, etc.
Yet the majority of stores/shops/companies don't integrate with it.
I personally would prefer to use Apple's native Wallet application over some 3rd party.
What we are going to see, is a bunch of 3rd party Wallet apps being pushed out their, that end up gathering your data, all because Apple didn't open up the Wallet app, and forced developers to produce their own solutions.
Don't confuse platform/backend with frontend application OS integration.
I've been a systems engineer for 20+ years and deal with many different systems on a daily basis. So I understand how things can and could work.