The more I think about it, the more I believe Benford's Law can be violated too easily within more urban areas, especially when precinct sizes are artificially limited to a fixed size (500~1000 people) without geographically-induced truncations. As long as voter turnout is consistently above 10-20%, with the 2-party system you're simply not going to get the vote count number to span the several magnitudes needed to induce Benford's Law. (Exception of course for smaller/independent candidates, and perhaps if one of the major candidates really sucked and kept getting 10% of the votes)