https://www.youtube.com/watch?v=m9HG_3SIsEM
So, your gas pump has to be accurate for the first five gallons, but then you can cheat as much as you want.
The only saving grace is that the people who make the pumps and software wouldn't be the main benefiters from cheating at the pump. So probably we're actually okay for gas pumps. It's situations where the software creator also benefits from the sales using that software...
But maybe I'm wrong. Maybe independent gas station operators are buying bootleg software ROMs to flash their pumps... "Boost revenue by 10% with this one easy trick"
And, I see from another comment: