I think people are used to just scrolling to an icon on their home screen and tapping on it, and companies like Apple/Google don't really like the idea of PWAs because they lose control over the developers and walled garden ecosystems they have created

Developers will optimize for what feels natural to the user, i.e. installing an "app" which doesn't require typing an address in the browser or scrolling through bookmarks

Also some companies from the developer side will want that extra user control that you don't have in the browser, for example to track them more, play unskippable ads, or access to some native features on the phone which are not available in web apps