How is a person standing in line to buy a pack of Marlboros any different than a person standing in line to buy a bottle of Pepsi?
Because they can't decide which brand or type they want. Then the store doesn't carry it or the cashier can't find it. Then they change their mind. Then the cashier has to go to the back to check. Then they decide on another. Then the cashier has to dig around for a new carton from the bottom of the counter and figure out how to open it. Then they decide they'd rather have the whole carton after the cashier has pulled out one pack and has taken forever reloading the bin. Then they spy what they originally wanted. Then they have to turn the pack over 3-4 times in their hands to make sure it's... well, who knows. Then they smack it on the counter once, twice, no 3 times real fast. Then they think about opening it. Then they decide to open it. Then they shake one out and put it in their mouths. Then the cashier has to tell them they can't smoke in the store and remind them they haven't yet paid. Then....