I actively don't want third-party payment systems on my phone. I also actively don't want the ability to load and run arbitrary third-party applications on my phone. Adding these things would make my user experience worse, not better.

My phone isn't a general-purpose computer in the way that my laptop is. My phone is an appliance. When I use my phone, I'm not actually using the phone itself, I'm using the email app to manage my emails, or the web browser to look at some news website, or Instagram to watch some reels, or Slack to communicate with my colleagues, or etc. The phone is just a conduit for apps/workflows.