The California State Board of Equalization tends to check dispenser accuracy.
I was told by senior SBOE manager Jimmy Hatlin, in 1976 that an overwhelming majority of dispensers caught repeatedly in error belonged to Franchises operated by minorities located downtown in big cities. He recalled one in San Francisco caught 11 times in (don't remember) months.
The fine was $40,000. The man was banned from operating the franchise so his sister took the reins and a month later the dispenser errors started anew.
Hatlin was a sharp cookie at catching weights and measures fraud. He was African American.
It's been 40+ years but I still miss his wisdom.