People who can't use commas correctly, are maddening. They also can be costly. The blog Priceonomics recently told the story of how one misplaced comma cost the government the equivalent of $38.4 million.
The whole story is fascinating and totally worth your time, but here's the quick version: at the time, tariffs brought in a huge share of government revenue. And up through 1872, the US government's tariff act specified that certain things were exempt from import tariffs. Among these were "fruit plants, tropical and semi-tropical for the purpose of propagation or cultivation."
That's plants, mind you, and not fruit itself. Getting fruit was expensive back then — the 1870 tariff act imposed a 20 percent tariff on grapes, pineapples, lemons, and oranges, and 10 percent on a whole mess of other fruits.
Then in 1872, the new tariff act contained an unfortunate comma that changed everything:
Now, with "fruit, plants" instead of "fruit-plants," all those pineapples and lemons and everything else were exempt from tariffs. And that typo would cost taxpayers $2 million — the equivalent of around $38.4 million today, and around 1.3 percent of all tariff income. Congress debated but ended up resignedly allowing the comma to stay. However, they did restore the tariffs in later acts.