The filter is only applied to custom columns that are added by you (or plugins and themes), not the default columns. If you want to modify the output of all default columns, I think you may have to add your own columns and duplicate the functionality of the defaults, then unset the defaults via manage_users_columns, since not all of them have filters to let you modify the values. When in doubt, dig into the source code and do a search for the filter to see it in context.
