Well, a count of 3 for unregistered login votes vs. 10 for registered login votes IS a way of encouraging participants to _register_ ... it really ISN'T "unethical", tho 'disclosure' might help...
Weighting votes, as long as it's done openly and evenly is simply a _choice_ made by those running the site.
10 versus 3 is not a fair distribution of weighing the votes. Try 10:1. And the background software is going to split the votes into the proper classification, so why have a weighing system except to impress the users?