Which are far larger numbers than the percentage of the population that will actually vote in Democratic primaries. I love news myself, but most folks learn enough to get by for the decisions they need to make.
People make decisions with lots of imperfect info-- what friends think, what political groups they trust tell them, and so on-- which may not be ideal but is probably not as bad as these pop quiz type of surveys indicate.
The key is to target local opinion leaders, neighborhood activists and others who in turn will influence friends and neighbors. You may only have a minority of voters well informed on the issues, but if the rest of the population is well-informed on whether they can trust the values of insight of those key local vote influencers, then you still end up with well-informed voting patterns.
Nathan