Cuz they look like stamps!
I have to admit, I was really disappointed to find out they weren't stamps with a turkey leg or eggs and milk on them. I totally thought as a kid the people at the grocery store took your stamps put them in a book and that was how people on foodstamps paid for their food.<br />
I thought too much as a kid...
Most states actually, paper foodstamps aren't really used at all anymore.
um, the same word can be used for multiple things... and there always have been all sorts of stamps... not just postage