Why are bit.ly URLs less spammy than tahoe caps?

[Imported from Trac: page NewCapDesign, version 32]

NewCapDesign.md

@@ -144,6 +144,7 @@ established sense). To make them real, we need to:
      I totally understand the skepticism; however, in this case there's nothing to be done, I think.
      -midnightmagic
     * Perhaps Human-meaningful urls support the Users' belief that they know "where they're going".  If a url is not human-meaningful the fact that the associated location is actually opaque is made uncomfortably apparent. -zancas
+    * I find it strange that people would trust bit.ly urls but not tahoe caps. Bit.ly, in particular, seems to be "public by design" and makes it difficult to even find their privacy policy that explains this.  You can shorten a tahoe cap with such a service, but you then have to trust the service -- a very scary proposition, IMO. --Terrel
  * Enable convenient cut-and-paste. If caps are too long they'll wrap in
    email. If they contain lots of word-breaking characters then you have to
    drag after you've double clicked (this is probably ok). If the word-broken