Aka americans? Of course there are americans that can't grasp the concept of timezones, as there are people like that worldwide... Why only list americans? Also, America (USA) has more than just one timezone... As you probably know, so americans are usually taught timezones in school. I learned them when I was 6. I have not met an American that doesn't know the timezones... So your post and point is quite invalid. On another note, I currently live in the UK and I was surprised at how many people couldn't understand that if they are on xbox with an american that it could be 7pm for the UK player but 1pm for the american....
I sometimes forget how many hours New Zealand is from my time zone. [spoiler]i think it is ~7hrs earlier/17 later[/spoiler]
But as for people not grasping the concept of time zones I say, "wtf dude, really?"