How can you be monopolistic without having a monopoly, however? Apple has far less than 50% market share in all the markets it operates in (except, maybe, for smartwatches...).

The majority of people does not seem to have a problem with being "locked-down" by Apple: they just buy an Android phone and Windows PC instead.

Google is very different - it has the by far largest mobile OS share and in some markets more than 90% search share. If you are a web (or -- thanks to Google Maps -- physical) business, Google can make or break you and there is nothing you can do about it. If Apple doesn't like your app, you can just develop it for Android. If Google doesn't like your webpage, no one will find it.