Pricing 101

How is this legal?


Is it legal for those gas stations to have a higher price without advertising that price? I thought it was 100% illegal for any company to advertise one price and then charge another price, for whatever reason. If they displayed both prices, I know it is legal to charge differently for using a credit card, but this video looks as if there is no displayed price difference, how then is this legal.

Too bad I don't know any competent lawyers.