That is crazy. Most places have bills automatically generated or billing outsourced by people who make money off the number of bills they send out who don't care what the amount is because they get paid the same.
Here is a thought on some of the larger companies billing and credits.
Say AT&T is owed $1 from 1 million of its millions of customers. If they let that slide they are losing $1,000,000 in revenue. In the reverse, if they owe credit of $1 to 1 million they are skimming $1,000,000 from their customers. Anyone going to allow that? Pennies add up!
On a smaller scale, 2000 customers owe $.50. That is $1000. Don't know about you, but I'd miss it!