The penalty scales with the number of bot accounts, but even Bill Gates can only drive one automobile at a time.
The USPS has a fleet of many (hundreds of thousands?) vehicles, so their capacity to ruin it for everyone is much larger - but their potential liability from fines is too. So they treat it very seriously.
The poster is saying that spam is more like the USPS situation, where single entities control thousands of potential infractions, not the rich individual.