We can probably all agree that lettuce, as a product, is a commodity. If there is a head of lettuce sitting on your kitchen counter, it could have been purchased at any store, with any providers brand name, and there is nothing to differentiate it from another head of lettuce...
We trade in older cars for new ones and we move to bigger (or smaller) homes to fit our lifestyle needs. Now, increasingly, we work with customers on trading in their obsolete benefit products for new ones.