Its definitely a problem that has risen in our colourbond modernity. In other words, i blame the lowering levels of community participation for the fact many people don't know who they're voting for.
Edit: I also think many council areas have too many people in them. I haven't looked at it, but i bet number of councils has not matched population growth. So how is someone supposed to know a set of 5 or 6 candidates from upwards of 10,000 people in their area? Be lucky if you know one or two.