apk doesn't warn if package already installed as a dependency
$ sudo apk add glib-dev
OK: 1408 MiB in 417 packages
$ sudo apk del glib-dev
World updated, but the following packages are not removed due to:
glib-dev: gtk+2.0-dev .makedepends-palemoon dbus-glib-dev cairo-dev pango-dev harfbuzz-dev gdk-pixbuf-dev atk-dev
</code>
According to install task above, glib-dev’s installation status is not
clear. apk should warn that package is going to be added as a
stand-alone package to /etc/apk/world.
Otherwise package and its dependencies will kept by system all time
without any awareness.
(from redmine: issue id 9956, created on 2019-02-03, closed on 2019-02-03)