duh, but it's ed up to give a distance advantage to a certain demographic group that will obviously be critical to your party/candidate winning over the other. it's not like whites or upper-class people are more likely to be willing to drive 10 miles (especially in CA traffic) versus walking 2 blocks any more than minorities or lower-class people.
Obviously one voter = one vote, but if person A has to go out of their way to get their vote counted and person B doesn't, then the chances of person B voting are much higher than person A voting regardless of which ethnic or socioeconomic demographic an individual is in.