没有省略成分。这是一个含有原因状语从句的复合句，主句中又含着一个比较从句。为了更好理解，我把主句补充完整，把because 从句中的成分调换位置：

Reading a book requires more intellectual efforts than watching TV, because with less visual and auditory aids we have broader scope of imagination.

= Reading a book requires more intellectual efforts than watching TV does （=requires）, because with less visual and auditory aids we have broader scope of imagination.

= Reading a book requires more intellectual efforts than watching TV does （=requires）, because we have broader scope of imagination with less visual and auditory aids.

【翻译】读书比看电视需要更多的脑力劳动，因为（读书）用较少的视觉和听觉辅助，我们有更广阔的想象空间。