The same way any business does.In this case, they hire very unskilled (and cheap) labor. They mark their products up a lot. That is why people dont grocery shop at them..--Answer1:My experience has been Convenience stores have a higher mark up and serve a select customer market.However, if they dont continue to offer what taht selecty market demands/needs... they will loose their customers and their profit margin.At times, they need to be very flexable... longer hours, more selection, loss leader items... etc....--Answer2:Who stole your teeth?