sometimes there is.

i.e. there is an intersection by me that has 3 gas stations on it. They used to have identical pricing. Then one station started charging the same amount for credit card transactions as it did for cash(other stations had cc transactions cost 10 cents more per gallon)

result? that station is always packed...there is a line to actually get gas...while the other stations barely have any business.

So it costs them 10 cents out of $3.70 a gallon or 2.7%(you know the actual cost of cc transactions..that every business in the world pays without a second thought) to get market penetration.

And since now the cost of gas is pretty high, they are getting a ton of money, since every fill up gets them $40-80