Touch John Tyner’s junk, and he’ll have you arrested. But help yourself to Tyner’s wallet, and you’ll hear nary a peep. Instead of rebelling against routine screening procedures, why won’t air travelers rebel against the opaque pricing of airline tickets?

Airlines always charged a little extra for headphones or one of those tiny bottles of scotch. If you put your 10-year-old on a plane without a chaperone, the airline would charge you for having to keep an eye on him until grandma collected him in Miami. But during the last two years, the airlines have been laying on fee after fee after fee, and typically you don’t hear about it until you’re at the airport and already settling into the zombielike state to which the physical discomforts and petty inconveniences of commercial air travel reduce us all. (Junk-touching is the least of it.)

The airlines lay on fees for three reasons. First, it allows them to make your airline ticket look cheaper than it really is, since all the customer typically knows when purchasing a ticket is the basic fare. People don’t have a lot of money to waste in this economy, and airlines want them to think they’re getting a bargain. Second, the laying-on of fees reduces the impact of price competition among airlines, since airlines compete only on basic fare, not on fees. Third (and least widely known), fees represent a tax dodge for the airlines. The Federal Aviation Administration charges a 7.5 percent tax on every ticket sold for domestic air travel. This tax is (with a few exceptions) levied only on the basic fare; divert some cost from the fare into a separate fee, and the airline reduces its tax burden. All the Internal Revenue Service requires is that the separate airline fee be unrelated to the transport of a person. (If it is related, like the unaccompanied-minor fee, then it gets taxed, too.) According to the Government Accountability Office, the two biggest fees—the baggage-handling fee and the reservation change or cancellation fee—brought the airlines $7.9 billion in untaxed revenue in 2008 and 2009. (Even so, U.S. airlines collectively accumulated $4.4 billion in operating losses during those two years.)

Now let’s review what some of these fees are. Many thanks to Smarter Travel, Kayak, and Fare Compare, whose helpful charts informed what follows. (I verified independently all specific prices cited below.)

Baggage-handling fee. The most familiar fee because it’s the most conspicuous. JetBlue gives you one bag free, and Southwest (bless ‘em!) gives you two, but most airlines charge $20 to $25 for the first and up to $35 for the second. Airlines really don’t want you to bring a third bag (Can you blame them?) and therefore typically slap these baggage-hold-hogs with a $100 fee. According to the Department of Transportation, Delta Airlines raked in the most baggage-fee revenue among domestic carriers ($474 million) during the first two quarters of 2010. That doesn’t mean Delta is the greediest domestic airline; only the biggest. Next in line are American, ($281 million), U.S. Air ($256 million), Continental ($168 million), United ($156 million), and … AirTran ($74 million)? How did AirTran place sixth? I would guess it has something to do with a luggage policy that, in addition to charging $20 for your first bag and $25 for your second, hits you with an “overweight” and/or “oversized” baggage fee of $49 to $79 if your bag is unusually heavy (i.e., more than 50 pounds) or unusually big (more than 61 square inches).

Don’t-phone fee. The novel theory of this charge is that you should have to pay extra to the airline merely for the privilege of buying something from it. Or rather, buying it by phone. That’s how people bought plane tickets during the 20th century, but now the airlines would prefer that you make your purchase online. Most people with a computer already do this, so the fee is essentially a tax on people who either don’t have a computer or don’t know how to work one. That is to say, it’s a tax (typically $10 to $20) on people who are either poor or elderly. United must have a particular aversion to talking to its customers by phone, because it charges $25 for phone reservations. Airlines most especially don’t want to look at your fair visage while selling you a ticket, dear reader, and therefore will often nail you with a fee of up to $45 if you buy a ticket at the airport. Never mind that no one ever buys a plane ticket at an airport unless he or she really, really needs to.

Reservation-change or cancellation fee. This isn’treally new. Airlines for some time now have been resistant to any change in travel plans, for the obvious reason that an empty seat represents lost revenue. Fees to change or cancel a ticket typically run from $100 to $150. AirTran and Virgin America take a more forgiving line, charging $75 and $50, respectively.

Food charge. The intriguing aspect of food charges on airlines is that they create the perfect laboratory for any economist who wishes to study the question of how to price a good that possesses, by universal consensus, absolutely no objective value. Answer: very, very low. Lower, in fact, than a meal at McDonald’s—which, after all, represents something that a person might actually want to eat. If you’re parched with thirst, the flight attendant will still give you a cup of water free of charge, I think.

Legroom fee. This fee is reminiscent of an old Borscht Belt joke. Three elderly Jews seated together in a restaurant each order a “glass tea.” The third guy is a little persnickety and says, “And please, in a clean glass.” When the waiter comes back 10 minutes later, he says, “Which one of you ordered the clean glass?” (Bada-boom.) Having filled their airplanes with seats packed closer than human beings were ever meant to endure, some airlines are now marketing more (i.e., marginally bearable) legroom for an additional fee. Continental, for instance, will give you a variable amount of extra legroom (minimum: 7 inches) for a variable price. In March, an Associated Press story quoted a Continental spokesman saying that extra legroom purchased on a flight from Houston to New York would cost $59. The spokesman didn’t quantify this extra legroom, but if we assumed the minimum 7 inches that would come out to a little more than $8 per inch. United is stingier with extra legroom—it offers only 5 extra inches—and pricing is all over the map (Chicago to Madison: $9; San Francisco to Las Vegas: $24; Denver to Seattle: $49). JetBlue markets special “Even More Legroom” seats for “as little as $10 more” (and as much as …?).

Blanket fee. This is a variation on the “clean glass” joke. Airplanes are cold, and there isn’t much to do on them except sleep and read. Both activities usually require a blanket. American will give you a blanket and pillow for $8, JetBlue and US Airways for $7. *

Airlines insist all this information is readily available on their Web sites. “Airline fees are not hidden,” they told the Transportation Department this summer in response to a proposed rule requiring a smidgen more disclosure than they provide today. But it’s actually quite hard to find fee information, scattered as it often is among different pages of an airline’s Web site. JetBlue, American, and U.S. Air hid their information about blanket fees so well that I never found it, and had to rely on news reports. You think maybe they’re just a wee bit embarrassed? The next time John Tyner goes to board a plane, his junk may or may not get touched. But if he doesn’t have $8 for a blanket, it will definitely freeze.

Correction, Nov. 23, 2010: This column originally stated that JetBlue charges $12 for a blanket and pillow. In addition, it also stated that JetBlue will rent you the blanket and pillow. It will sells them for that price. (Return to the corrected sentence.)