A whole lot of marketing studying goes on regarding what to place at the check out aisles. First, it has to be small enough to stock a lot of items in a small space. Then they have to be items that people will buy on impulse; i.e., magazines, candy, and household junk you never knew you "needed." The chances of getting something healthy to eat there is kind of remote.
But one thing I noticed is that a lot of the stores around here offer the self service check out -- and there's nary a candy bar or magazine or nail clipper in site because even if you have to wait for a register to open up, it's likely to be faster than the staffed checkout lines.
I've gotten to the point when I'm in line that I get out the checkbook to write down the purchase even if I'm using a debit or credit card, then I check on email, then I check on FB, then I check on 3FC. If I'm still in line at that point, I vow never to return to the store. But it does keep my grabbing little hands busy.