Consumers have pilloried U.S. airlines over a wide range of injustices lately: high fares, low customer service, predatory baggage and other fees, crowded planes and even crying babies. Here’s one more insult to add to the list: Airlines have now become the Grinches that stole passengers’ tax holiday.

For every airline ticket, passengers pony up a 7.5% federal tax on the base ticket price, a domestic segment tax of $3.70 and a 6.25% tax on property being transported by air. There’s also an international facilities tax of $16.30 per person for flights that begin or end in the U.S., and an $8.20 tax for flights that begin or end in Alaska or Hawaii.

Or at least travelers paid those taxes until July 22, when Congress failed to reauthorize funding for the Federal Aviation Administration. The agency temporarily lost federal funds that pay for many of its operations — and the authority to collect those federal airline ticket taxes.

Here’s where the fun begins: The IRS, airline passengers and many members of Congress considered it a no-brainer for airlines to give travelers a break by passing on the tax savings. Most airlines, however, had other ideas. The vast majority of U.S. carriers simply increased their ticket prices and pocketed the cash — a windfall that adds up to $29 million a day.

Delta (NYSE:DAL), United Continental (NYSE:UAL), US Airways (NYSE:LCC), Southwest (NYSE:LUV) and JetBlue (NASDAQ:JBLU) raised ticket prices to keep the tax break. In its quarterly earnings conference call last week, Delta executives boasted they were raking in $4 million to $5 million a day from the practice. Alaska (NYSE:ALK) and Spirit (NASDAQ:SAVE) chose to pass the tax benefit on to their passengers.

But as Sir Isaac Newton famously mused, “For every action, there is an equal and opposite reaction.” Passengers have responded with howls of protest, the IRS has urged airlines to refund the money and even Congress — which ironically set this latest airline fracas in motion — is now railing against the industry.

During a subcommittee hearing on aviation biofuels last week, Senate Democrats put airline industry lobbyist Sharon Pinkerton on the hot seat, demanding to know why airlines were not passing the savings on to consumers.

Pinkerton’s response was revealing of the disconnect between industry practices and consumer perceptions: “The airline industry is sick; it’s anemic,” she said. “Our revenues have to be able to cover our costs. … Some carriers made individual decisions to keep the total ticket price the same. Customers are paying this week exactly what they were paying last week before the funding lapse.”

That disconnect will add to the industry’s problems — particularly because rising consumer wrath heading into an election year can motivate lawmakers to woo voters by tightening the screws on America’s most hated industry.

While chagrined consumers will not forgo planes in favor of trains or automobiles, they will reward the “good” carriers and punish the “bad.” By passing along the tax savings to passengers, Spirit reported its ticket sales had risen by 22% in just the first three days; Alaska reported a notable increase in bookings because of the policy.

After a stern talking-to by the IRS, Delta reversed its position this week and has promised to process tax refunds for passengers who bought tickets during the lapse.

As of this writing, Susan J. Aluise did not hold a position in any of the stocks mentioned here.