Personally I wouldn't even consider an LS without Nav, ML etc...Might as well buy a loaded Camry.

 

I have seen versions of luxury cars in the past that should have navigation by default but don't. It leads me to the conclusion that it's not a cost cutting measure to make a particular trim more affordable but something else otherwise they would not go though the trouble of filling out the dash where the navigation should be.
I bet it's some corporate fleet tax loophole and the lack of navigation is some kind of qualifier.