Well that certainly is your right. But it is exactly the explanation to your question. Your entire argument that competition doesn't exist because gasoline prices are not different really doesn't fly.
Two competing station on opposite corners selling gas for $1.00 wouldn't be competing for your money using your logic. What about two stations selling a gallon for a nickel? Are they not competing? In fact using your logic, if these two stations were both paying you $1.00 for the privilege of filling your tank they wouldn't be competing.
The fact is that one may be paying more for his product, but he also sells more coffee and Hostess Donut Gems allowing him to match his competitor's lower price.