Why are their sim cards at the till point?

I can't immagine how some of the managers of Checkers stores think. When you are standing at the till points they have cellular sim cards available at the till points, however you can not pay for these items at the till point. No Sir you have to pay for this specific item at the moneymarket counter, why are they then on display at the normal Till Points if you can not pay for them at the Till Points. Really does not make sense