Reading a ticket works without logging in, but only if you know the URI (e.g., https://www.fossil-scm.org/index.html/tktview?name=...).  If you don't know it, then the list of tickets tantalizes you with a summary and a hex name but there is no link to the full ticket page.  Why disable the links for users who haven't logged in?  I know I can log in anonymously, but having to do so just to browse tickets seems an arbitrary and superfluous barrier.  It probably also means that search engines won't index the tickets.

<hr /><i>drh added on 2011-06-02 18:52:24 UTC:</i><br />
Providing open access to tickets without anonymous login is a configuration
option:  Simply turn on "History" privilege to the special user "nobody".

We deliberately choose to not do that on the Fossil website because the 
internet is a hostile place and spiders would overrun our bandwidth quota if
we did.