gas tanks

Can anyone tell me why the gas tanks are not on the same side on every car!
You see I have about 4 cars I drive routinely. The state car (some of the state cars have tanks on opposite sides), my car, my hubby's car and my daughter's car. Then of course sometimes am asked to drive someone else's car because they are sick or whatever.
Then I have to get gas, which side of the car is the tank on! Invariably I drive to the wrong side of the gas pump! Not so much of a problem in NJ as we have folks who pump our gas(believe it or not) But then there are the other states. One gets out of the car and oops I did it again- have to get back in to pump my own gas!
Next problem I have encountered with this, is you drive to the gas station, which line is the lowest! Get the car on the right side etc. etc.
As Americans we pay a plenty for gas (not as much as foreign countries, but it makes a hole in ones pockets. Along with coming up with a more efficient- fuel saving car! Can't the car makers and pump makers make those darn gas tanks uniformly on one side or the other!