One way we addressed the former was to put up signs that say "Drive Carefully", so apparently your dislike of that technique is not universal. It's called a "nudge", and it has significant (but limited) effect.
I'm not disputing that, but sometimes when we weigh our actions, significant (but limited) alternatives will not cut it, and if the effect is limited enough (and the problem severe enough), even deliberating on them will waste precious time to enact direct and (hopefully) effective action.
Woah, so even debating this issue is wasting precious time? I know this seems to be super-important to you, but for someone who complained about getting short shrift (in another comment), you might try using different language next time.