If the marked text in VisualEditor's "Add a link" feature is an exact case match to a page name then that name should be shown in the suggestions whether or not it's a redirect and whether or not there is another redirect with different capitalization.
On enwiki, "United States of America" and "United states of america" are redirects to "United States".
If you start VisualEditor's Add a link feature on the chain icon with "United States of America" then the suggestions include the poorly capitalized redirect "United states of america" but not the better "United States of America" as you started with (see screenshot). You can create that link by clicking "Done" or pressing Enter but users may not know that, and they cannot see it will work or where it will go. A non-existing page name would look the same in the feature but produce a red link on "Done".
The issue was brought up at https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Strange_linkages,_piping_through_miscapitalized_redirects (permanent link, archived discussion)
The missing suggestion causes many VE users to make pointless piped links like [[United states of america|United States of America]] (example)
It probably also causes many VE users to waste time looking for a way to make the link they wanted.