Need a elementary explain along with a WHY, really confused on this and how to accurately figure this out

Since the gas volume is measured, i.e., a continuous variable, you know even in perfect lab conditions, if you take measure of the supposedly 1 gallon of gas pumped out the of machine, it will never be exactly 1.0000000... gallon. So if it turns out to be 0.9823, can you say the gas stations are cheating? You might say I will take 30 measurement and look at their mean, but again if it turns out to be 0.9912? can you say they are cheating? How you would go about verifying whether a gas station's pump is accurately dispensing gas. Also, what will be the difference in investigating whether a gas station is intentionally shorting customers vs a gas station's pump is simply out of calibration due to neglect