Airlines may be collecting billions of dollars via charging additional fees for carry-on and checked baggage, preferred seating and early boarding, but the lack of transparency has passenger dissatisfaction on the rise.

According to a government report, fee income totalled around US$7.2 billion last year for United States airlines. A lot of travellers complain about buying tickets with low published fare to be later hit with additional charges in what is often described as "bait-and-switch" tactic.

According to a report from the United States Government Accounting Office, passengers who paid for bags and airline seats separately were likely to pay a higher total sum than when checked bag privileges were bundled into ticket prices.

A study from Charles River Associates for Travel Technology Association also found: unbundled fares cost about US$30 more than bundled prices.

Recently, a UserTesting report found that Southwest Airlines, which doesn't charge for the 1st or 2nd checked bag, scored highest for customer satisfaction, while Spirit Airlines (charging extensive fees) scored the lowest. Determining the final cost of flight was said to be the most frustrating aspect of buying an airline ticket.

The United States Department of Transportation is considering new rules in order to compel airlines to disclose much more fee info on websites where tickets can be bought. The airline industry, understandably, opposes the regulation.