rtfm

 When the output is not a TTY, the progress bar always falls back to
 "dot", even if --progress=bar was passed to Wget during invokation.
 This behaviour can be overridden and the "bar" output forced by
 using the "force" parameter as --progress=bar:force.
 By default, the bar style progress bar scroll the name of the file
 from left to right for the file being downloaded if the filename
 exceeds the maximum length allotted for its display. In certain
 cases, such as with --progress=bar:force, one may not want the
 scrolling filename in the progress bar. By passing the "noscroll"
 parameter, Wget can be forced to display as much of the filename as
 possible without scrolling through it.
[...]
--show-progress
[...]
 By default, wget only displays the progress bar in verbose mode.
 One may however, want wget to display the progress bar on screen in
 conjunction with any other verbosity modes like --no-verbose or
 --quiet. This is often a desired a property when invoking wget to

De plus, si le seveur http ne renvois pas d'information sur la taille de fichier, tu ne pourras pas avoir de barre de progression...