Have seen the pointer discussed on car forums in the past and it seems that they don't always point to the side the filler is on. On two vehicles we have the arrow is on the correct side tho.
What IS annoying is that sometimes a windshield wiper stalk is on the left side of a steering wheel and sometimes it's on the right. Same with cruise control buttons. Can't they standardize this stuff?
I have a '50s vintage car with the gas tank and filler in the front trunk like in the photo . A few times when I've pulled into a gas station I've gone inside and watched the guy look everywhere for the filler. Waay fun. :)