Stupid people. If we could have a cull or legalise post-natal abortion, then if we just got rid of all the stupid people then we'd instantly have a better world.
Everything else that people have mentioned on this thread anniys me too, but at least I can understand the reasoning behind most of them (politicians want more power, drivers can't be arsed to use their indicators etc), but there is literally no benefit to being stupid. Hitler had the right idea, he just picked the wrong group of people.