Well, if you put it that way... :)

Seriously: There are several reasons -- aside from the content of the node -- why a node's reputation isn't a valid reflection on its value:

1. Nodes have different values to different people. What you find vote-worthy, others might not.
2. Replies that get posted late in a discussion have fewer eyeballs going over them, and thus have less of a chance of garnering votes. There are some great nodes that were posted weeks or months after a discussion was over.
3. Replies that happen deep into a discussion are often overlooked by people who haven't taken the trouble to figure out what Some notes below your chosen depth have not been shown here means. (See here for one explanation.)
4. Once a discussion goes on for a while, and some good answers have been posted, people might just give up on the thread, believing that it's been well mined out. I catch myself losting interest in some threads once they descend into Perl golf.
5. It may be the case (i.e., here's a hypothesis) that votes from East Coast monks get used up earlier in the day, and aren't available for the many excellent posts made by West Coast monks.
6. Etc., etc. (See jcwren's post below for more good reasons.)

The point is, in general, the number of votes that a node gets is not a great reflection of a node's "value". And I don't think anyone is highly motivated to try to make the situation "fair", at least not once they've thought through the implications.

But life here is more interesting at the edges. Nodes that gather high scores (Best Nodes)or negative scores (Worst Nodes) are worthy of study, not so much for the value of the node (though many of the highly ranked ones are indeed quite good), but as a read on the "pulse" of the monestary, and for tips on which styles of writing and rhetoric people respond to.