My guess? Conservatives think about consequences, Lefties think about reward. Eat what you want in small amounts and you'll likely stay fit/not obese vs eat whatever you want whenever you want and you'll be slobbishly obese in no time. Exercise vs sitting on ones arse at Starbucks. Reading the news versus reading the headline. On and on we could go.

Consequences of actions tend to prevent that action from occurring, while rewards for actions tend to lead to that action being done.