I'd ask the opposite instead, what is it that leads people to AMP over "the original"? I have never been directed to an AMP page except in case someone shares AMP urls. And I use a lot of browsers and search engines, just not chrome or google.
Google is quite vicious in displaying primarily AMP pages on mobile search results. There are times my inquiry only returns AMP pages, essentially requiring me to use another search engine or use the web as Google demands.
What leads people to it? Google. They intentionally kick you out of search results if you don't do AMP. The end user has very little choice in the subject.
For me Google news on mobile(firefox)loads every page as a AMP page. Very annoying.