We have seen the Scrooge, and it is us.

Both UPS and FedEx are getting excoriated for the huge delays in shipping packages this year, leading some people to have fewer gifts under the tree. Indeed, the companies clearly erred in two big ways. First, they planned poorly, failing to see the logistics challenges of this particular holiday season. Second, they overpromised, insisting they could meet deadlines even after they likely knew - or, given how loudly they preach logistics - should have known they could not meet their commitments.

But the shipping fiasco says something deeper, something more about ourselves: We are a nation that buys a lot of stuff late.

Related: Make the Most Out of Post-Holiday Sales

Anyone who ordered gifts in the first part of the month got them in plenty of time. The problems came for those who waited until the last minute to pull the trigger on purchases. More and more Americans are delaying their Christmas purchases, and I posit it is a trend that all businesses need to recognize. Our habits have changed, and retailers, shippers and manufacturers alike need to get used to it.

So why do we buy so late? Three reasons:

1. We are a nation of procrastinators. We know we shouldn't put things off until the next day, but we always say we'll fix it tomorrow. The availability of one-click orders, with guaranteed (well, almost guaranteed) delivery is addictive. Shopping online has not only precluded the need to fight the great unwashed at the malls but it also has allowed us to not think about shopping until we absolutely need to.

Related: Preaching the Morality of Capitalism

2. Retailers are discounting later. Since Black Friday now essentially starts on Labor Day, the whole schedule of discounting has changed. This season started out slow for retailers, but let's be honest for a second: When do we not hear that the season starts out slow? Retailers mark down merchandise as the holiday gets closer. The closer they are to being stuck with a product on their shelves after Christmas, the more likely they are slash that price. Like lions who know their dinner by the limp of a gazelle, consumers are quick to anticipate where their best bargains are. They stalk patiently, waiting until the last moment to snap up what is very often the best price. Retailers have fostered this Darwinian conditioning.

3. Americans are generous. Over the past seven or eight years, we spend 11 months talking about how bad the economy is, how high unemployment is and how weak the consumer is. Then, once we tally sales receipts, we are surprised to hear that folks went to the stores and spent money on other people. The American consumer always surprises. There is a simple, non-cynical reason for this: We are generous. We like to give. There is something fulfilling about gift-giving, about seeing someone's eyes widen when they rip open wrapping paper and see the present they actually asked for. Some rail against heavy consumerism at Christmastime, but folks forget that we give to each other, not consume for ourselves. This generosity feeds into late-season buying because many of us make our lists, check it twice and decide at the late hour that we need to buy more, for more people in our lives. There's many an American who decides in the last week that they need to buy just one more gift.

So are UPS and FedEx blameless? Far from it. They better than any other companies should understand and adapt to these changes in American buying habits. But consumers taking to Twitter and Facebook claiming the shipping giants are modern-day Grinches should spend a moment this Boxing Day examining what role their own habits had in stopping Christmas from coming. 

Related: Why Our Growing American Affluence Should Be Celebrated