I've been running my league for the last 5-6 years, every year, there are a couple teams that screw up their envelopes (over pay, short pay, whatever).  I get everything to balance for pay out night.  My father helps, so I have 2 people counting.  There's always at least one of the screw up teams that then complains, as if it's my fault that they can't do simple math ($28*33=$924, not hard math, is it?).  Then I'm called on to further fix things. 

I just don't get it.  Am I the only one this happens to?

I find that if you keep good records, there are less likely to be issues.  I check the enveloped each night and confirm what the bowlers wrote down, matches to what was in the envelope.  If anything doesn't match up, I discuss with the team that night, while it is fresh in their mind.  I also keep an excel spreadsheet to record what each team has paid.  So at a glance, I can tell what any bowler in the league is +/- and what their payoff for the season is.  The last few weeks, I'll put a note in each team's envelope saying what each bowler is + or -, and what they need to finish paying off the league.  This way, they can be made aware of their current financial position, even if they have trouble with the math.  At least for me, it eliminated any questions on payout night, because everyone knew exactly what their balances were on the last week.  I also put a little sheet in the payout envelope too.  Showing what each bowler was +/- on their dues, and what their fair share of the team's payout would be after subtracting any dues owed, or adding any dues overpaid. 

I have that breakout on the payoff envelope.  In one of my leagues, it is 4 person teams, but this team used a 5 man rotation.  So I listed how many weeks each person bowled and what the percentage of the prize fund each bowler would get based on that.  Of course, it is up to the team captain to pass out the money.  The team could have agreed to some sort of payout breakdown other than equal shares.  On each team's envelope, I put a summary of what everyone paid, what they owed and what their share will be.  So if they still ask how much does everyone get, then they are either lazy, or can't read, because the information is right in front of them on their envelope.   

Well then that sounds more like a "them" issue and not that you need to change anything you are doing.  I know the saying is there is no such thing as a stupid question, but when the answer is already right in front of them.....