Not sure what you are talking about (is this sarcasm?), but on iOS, Safari allows you to add any website as an item to your home screen. I am pretty sure Android has a similar feature.
Is that front and center in the UI? How many users know about this feature? Do they promote it as much as they promote other features they want to promote?
Location and marketing matter. Otherwise we're in the Hitchhiker's Guide to the Galaxy where the aliens put Earth's demolition notice on the bottom of a cupboard in a cellar on a planet light years away from Earth.
In what UI? I've definitely done it by accident as well as on purpose before.
Most people like apps because they're often better to use, unless you have accessibility requirements (and even then an app that makes sure accessibility is good might still be better than a website that makes sure accessibility is good).
Location and marketing matter. Otherwise we're in the Hitchhiker's Guide to the Galaxy where the aliens put Earth's demolition notice on the bottom of a cupboard in a cellar on a planet light years away from Earth.