Not sure how often it happens BUT pumps are checked for accuracy by some government dept.. can't remember which one
Maybe in NSW but NOT IN QLD !!
Pumps in WA have a sticker with the date and checkers number on it.
QLD Dept of Weights and Measures used to do it - that department no longer exists. Often in the past they would have a pump blocked off while checking - doesn't happen any more. Food scales in supermarkets were also regularly checked - no more !!
Have had numerous occasions where the 30 litre sub tank in my Patrol has supposedly taken up to 38 litres to fill ! WTF !! How come in WA I can only get up to 31 litres into it but in QLD it takes 38 litres?
I smell a RAT !!