Ernest and Dazzleman are partly right, that the economy has been good enough in the last quarter century that we don't worry much about the basics.
Gabu is partly right, that economics is a scientific dialogue, and social issues are an emotional one. No one would even think to say, "You ran up a budget deficit of more than 3% of GDP, you're a baby killer!" I'd like to add on to that, though, that so few people understand economics well enough to have strong feelings about it anyway. Its not hard to understand basically what gay marriage means. This is why foreign affairs issues can be a hot button sometimes, we all know what a war is, we don't all know what the Laffer curve is, so foreign policy fits this bill too.
What makes you think someone needs to understand the Laffer curve theory in order to vote on economic issues?
All he has to so is get tired of living on $7 an hour and have some poltician say, I'll make your minimum wage double that, and give you health insurance. The odd thing is that few politicians say that, and few of that downtrodden half or so of the population vote. But it has nothing to do with understanding various economic theories.