Was it really drivers mistyping?
From the article: "PayStay allows parking inspectors to check that payments have been made for a parked car." and "the typography used on car number plates issued in Victoria makes it all-but-impossible to distinguish a capital O and a zero"
Perhaps it was the inspectors who "innocently"* mistyped the number plates. I'd guess that the probability that an inspector knows how to use a keyboard but not how to interpret an ambiguous plate is greater than a driver not remembering a number plate or having difficulty with a keyboard.
* A statistical analysis of fines for non 0&1 number plates vs plates containing 0&1 might point to less-than-innocent checking of payments, but let's let Occam decide.