All those fees airlines slap on to check bags and change flights are adding up to big money. New figures show that U.S. airlines collected almost $5.7 billion in fees last year, a 10% increase from 2009.

The biggest fee hog was Delta Air Lines (DAL), which led the industry in fees for both categories, Reuters reports. In fact, Delta collected more than 20% of the entire industry's total. American Airlines, owned by AMR Corp. (AMR), came in second. You can see the full list here.

Check out the following video report about the fees.

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How important are these fees to airlines? Without them, they would be in sorry shape. U.S. airlines made $958 million in profit last year, all from baggage fees, according to The Wall Street Journal. "Bottom line to all the fees: The airline industry increasingly has built its financial model on penalizing its customers," Scott McCartney writes. "Not a recipe for lovable customer service."

So don't expect airlines to ease up on the fees anytime soon. In fact, many are just getting started, revving up their websites to offer destination tours, car rentals, event tickets and other add-ons. For a fee, of course.

Sometimes the fees aren't exactly clear to customers when they make reservations. How much is being charged and for what? The government has given airlines a deadline to provide more accessible bag-fee and fare information.

But the airlines are asking the Transportation Department to push back that deadline until next spring so they can train employees and upgrade their technology, Reuters reports.

All those fees aren't provoking real complaints, however. People are more satisfied with airlines than they were last year, according to a new study from J.D. Power & Associates. On a scale of 1 to 1,000, overall airline satisfaction climbed 10 points from last year to 682.

But satisfaction with airfares and fees dropped to 555 this year from 582 last year, The Los Angeles Times reports. JetBlue Airways had the highest overall satisfaction rating among low-cost airlines.

As if that weren't enough, now airports are saying they want to raise fees as well. Right now, airports can lob a $4.50 maximum fee on passengers, and they say that amount is too low, The New York Times reports.

"Airports should be permitted to charge a user fee at whatever level they can charge that would also work in the market," the president of a trade group representing the nation's commercial airports told the Times.