Free Offers: Why Only US and UK?

While surfing the Internet you can now apply for thousands of free offers. But what's more frustrating to me and I'm sure a lot of people worldwide is that most of them are only valid in US or UK. OK, sometimes also in Canada.:) Why is that? I know they have to pay more for post expenses but what if the person who applies for these offers is willing to pay those expenses? I think I wouldn't mind paying that if I could win 1 free iPOD or 1 free laptop! That's just not fair!