nesting instead of id ing

[Tim W]

I am looking at the site template here:
http://www.html5-templates.co.uk/archive/temps/beadysite/
The Nav menu is in the html like this:

<ul>
<li>
<h2>Menu </h2>
<ul>
<li><a href="index.html">home</a></li>
<li><a href="#">about us</a></li>
<li><a href="#">blogs</a></li>
<li><a href="#">arcade</a></li>
<li><a href="#">gallery</a></li>
<li><a href="#">links</a></li>
<li><a href="#">contact us</a></li>
<li><a href="#">forums</a></li>
</ul>
</li>
</ul>

And the Nav has no id but is selected in the css as
#sidebar li li {.... }

I realise the futility of sometimes looking for purpose and design in a
world in which meaning is almost always elusive but here is my question:
Is it normal or common this nesting of lists instead of giving them a
class or an id? I have never seen it before. And Why?

Tim W